Read the following passage and questions, then choose the right answer from options, the answer should be one of A, B, C, D.

<passage>:
THE BIG HEADACHE What's the principal cause of headaches? of all headaches." "That's what I meant to say. But I'm not sure it would be completely ethical with even a discovery partly mine." "You're right. Besides who cares if you or I are cured of headaches? Our reputations don't go outside our own fields," Mitchell said. "But stroke ... or at least a vascular spasm of a cerebral artery. It was known that he suffered from the vilest variety of migraine. A cycle of "Doctor, we understand you have severe headaches," Mitchell said. to do with my headaches?" from what you have said you mean headaches." "Headaches," Mitchell agreed. "Everybody has them at some time in his their headaches." could be cured of headaches forever by one simple injection." "I don't suppose the manufacturers of aspirin would like you. But it would please about everybody else." "Aspirins would still be used to reduce fever and relieve muscular pains," Mitchell said. "I see. Are you two saying you have such a shot? Can you cure headaches?" a number of different causes for headaches—nervous strain, fatigue, physical diseases from kidney complaints to tumors, over-indulgence—but there is one effect cause of headaches," Mitchell announced. produces headaches is?" telencephalon section of the frontal lobes. It's caused by an over-production of the pituitary gland. We have artificially bred a virus that feeds on pituitrin." "That may mean the end of headaches, but I would think it would mean the end of the race as well," Macklin said. "In certain areas it is valuable to have a constriction of blood vessels." "The virus," Ferris explained, "can easily be localized and stabilized. A colony of virus in the brain cells will relax the cerebral vessels—and only the cerebral vessels—so that the cerebrospinal fluid doesn't create pressure in the cavities of the brain." works, I could stop using that damned gynergen, couldn't I? The stuff makes me violently sick to my stomach. But it's better than the migraine. How should I go about removing my curse?" He reinserted the discovery will work." "Will work," Macklin said thoughtfully. "The operative word. It hasn't large-scale field test. But we haven't the time or money for that. We can cure the headaches of one person and that's the limit of our resources." means another attack of migraine. The drilling, grinding pain through it? You aren't much better off with it than without, are you? I've heard some say they preferred the migraine." All our test animals survived and seem perfectly happy and contented. As I said, the virus is self-stabilizing. Ferris and I are confident that there is no danger.... But we may be wrong." Mitchell or I cured ourselves of headaches—they might not even believe us if we said we did. But the proper authorities will believe a man of your reputation. Besides, neither of us has a record of chronic migraine. You do." injection." Mitchell cleared his throat. "Are you positive, doctor?" he asked uncertainly. "Perhaps you would like a few days to think it over." "Yes, we wanted to show our proof to the trustees—but not broadcast unverified results to the press. It's too early for that!" "Don't be so stuffy and conservative, Mitchell! Macklin's cured, isn't he? By established periodic cycle he should be suffering hell right now, shouldn't he? But thanks to our treatment he is perfectly happy, with no unfortunate side effects such as gynergen produces." "It's a significant test case, yes. But not enough to go to the newspapers with. If it wasn't enough to go to the press with, it wasn't enough to try and breach the trustees with. Don't you see? The public will hand down a ukase demanding our virus, just as they demanded the Salk vaccine and the Grennell serum." "But—" heroin." "That's absurd. What makes you think a thing like that?" Dean's twin except that he had received no injection of the E-M Virus, "Never mind, doctor. It was a form of humor. I think we had better see exactly what is wrong with Elliot Macklin." "There's nothing wrong with him," Ferris snapped. "He's probably just injection," he said. It wasn't a question. a heavy eyebrow. "No? Are you medical doctors? Are you authorized to treat illnesses?" "We weren't treating an illness," Mitchell said. "We were discovering a method of treatment. What concern is it of yours?" used to be a mathematical genius." "And now?" Mitchell said impatiently. "Now he is a moron," the medic said. "What did he mean, Macklin is an idiot?" Mitchell asked. "Not an idiot," Colonel Carson corrected primly. "Dr. Macklin is a moron. He's legally responsible, but he's extremely stupid." "I'm not so dumb," Macklin said defensively. But according to all the standard intelligence tests we have given you, your clinical intelligence quotient is that of a moron." "What have you done to him?" the colonel asked straightforwardly. "We merely cured him of his headaches," Mitchell said. "How?" Mitchell did his best to explain the F-M Virus. "You mean," the Army officer said levelly "you have infected him with some kind of a disease to rot his brain?" "No, no! Could I talk to the other man, the doctor? Maybe I can make virus colony overcontrols the supply of posterior pituitary extract in the cerebrum. It isn't more than necessary to stop headaches. But that necessary amount of control to stop pain is too much to allow the brain is replaceable. But the chances of an Elliot Macklin are very nearly once in a human race." "Just a moment," Mitchell interrupted, "we can cure Macklin." "You can ?" Carson said. For a moment Mitchell thought the man was going to clasp his hands and sink to his knees. "Certainly. We have learned to stabilize the virus colonies. We have antitoxin to combat the virus. We had always thought of it as a beneficial parasite, but we can wipe it out if necessary." "Good!" Carson clasped his hands and gave at least slightly at the "What do you mean you don't like it?" Carson demanded. He added, "Sir?" "I figure you mean to put me back like I used to be." "Yes, doctor," Mitchell said eagerly, "just as you used to be." my headaches, like before?" are millions of morons running around loose in the United States. They can get married, own property, vote, even hold office. Many of them do. You can't force him into being cured.... At least, I don't think you can." cure your husband of his present condition." he's certified incompetent, authorities can rule whether Mitchell and Ferris' antitoxin treatment is the best method of restoring Dr. Macklin to sanity." "There is some degree of risk in shock treatments, too. But—" "It isn't quite the same, Colonel. Elliot Macklin has a history of vascular spasm, a mild pseudostroke some years ago. Now you want to give those cerebral arteries back the ability to constrict. To paralyze. To kill. No court would give you that authority." "I suppose there's some chance of that. But without the treatment there is no Macklin," Mitchell interjected. Her mouth grew petulant. "I don't care. I would rather have a live husband than a dead genius. I can take care of him this way, make him

<question>:
How would the shot theoretically cure headaches?

<options>:
A It would address the root problem of every headache. By focusing on the core behind a headache, it can be used in any circumstance.
B It would separately address any problem that could cause a headache, from tumors to fatigue. It's built to be an answer to everything.
C It constricts the blood vessels with an artificial virus.
D It's not a cure at all, it's a virus.

<answer>:

A