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

<passage>:
Ranson passed the conventional electric eye and a polite robot voice books. As Ranson entered, he swung about, frowning, one hand dropping "You sent to Earth a while ago for an operator?" Jared Haller nodded. He was a big, rough-featured individual with gray leonine hair. A battering-ram of a man, one would think, who hammered his way through life by sheer force and drive. But as Ranson looked "Yes," said Jared Haller. "I sent for an operator. You got here quickly, Mr. Ranson!" Ranson put it directly. "Why did you require the help of T.I., Mr. Haller?" he asked. "Because we're up against something a little too big for the Mercian police force to handle." Jared Haller's strong hands tapped nervously told what crime had taken place. This time Ranson applied the spur of silence. It worked. "Mr. Ranson," Haller leaned forward, his face a gray grim mask, Ranson nodded, eyes intent as the pattern unfolded. weeks! Look here!" Haller bent forward, the lines about his mouth tighter than ever. "Three weeks ago my technical advisor, Rawlins, committed suicide. Not a care in the world, but he killed himself. A Declared a feud with the whole planet, began shooting at everyone he the musical director, died of a heart attack. Died with the most terrorized expression on his face I've ever seen. Fear, causing the heart attack, his doctor said. You begin to see the set-up? Three men, each a vital power in M.B.C. gone within three weeks! And who's next? Who?" Jared Haller's eyes were bright with fear. "Suicide, insanity, heart attack." Ranson shrugged. "All perfectly normal. Coincidence that they should happen within three weeks. What "One thing," he said slowly. "The music." "Music?" Ranson echoed. "Look here, Mr. Haller, you...." "It's all right." Jared Haller grinned crookedly. "I'm not insane. Yet. Look, Mr. Ranson! There's just one clue to these mysterious deaths! And that's the music! In each instance the servants told of hearing, ever heard. Like the devil's pipes, playing on their souls, while.... Almighty God!" Jared Haller froze, his face gray as lead, his eyes blue horror. Ranson was like a man in a trance, bent forward, lips pressed tight until they resembled a livid scar. The room was silent as a tomb Neither man moved. Ranson knew all the tricks of visual hypnotism, the shards of sound pierced their ears, deep throbbing underrhythm shook them as a cat shakes a mouse. "God!" Haller snarled. "What ... what is it?" Suddenly the elfin melody changed. Fierce, harsh, it rose, until Ranson to kill ... kill! Blindly he whirled, groping for his gun, as the music rose in a frenzied death-wail. Turning, Ranson found himself face to face with Jared Haller. But the tall flinty magnate was now another person. Primitive, atavistic rage his master, and it was driving him to frenzy. "Kill!" the weird rhythm screamed, "Kill!" And Jared Haller obeyed. He snatched the flame-gun from his pocket, levelled it at Ranson. Whether it was the deadly melody outside, or the instinct of self-preservation, Ranson never knew, but he drove at Haller with grim fury. The flame-gun hissed, filling the room with a greenish glare, its beam passing so close to Ranson's hair as to singe it. Ranson came up, grinning furiously, and in a moment both men were struggling, teeth bared in animalistic grins, breath coming in choked gasps, whirling in a mad dance of death as the macabre music distilled deadly poison within their brains. The end came with startling suddenness. Ranson, twisting his opponent's arm back, felt the searing blast of the flame-gun past his hand. Jared Haller, a ghastly blackened corpse, toppled to the floor. At that moment the lethal rhythm outside changed abruptly. From the fierce maddening beat of a few minutes before, the chords took on a window. Twenty feet to the ground, almost certain death ... but Ranson stopped. Ranson shook himself, like a man awakening from a nightmare, disappeared among the twisting narrow streets. Bathed in cold sweat, Ranson stepped back into the room, where the still, terrible form of Jared Haller lay. Ranson stared at it, as though seeing it for the first time. Outside, there were pounding feet the canal-patrolmen raced through the house, toward the study. And then, his brain weary as if it had been cudgelled, Ranson slid limply to the floor. arcs. Captain Maxwell chewed at his gray mustache, staring curiously at Ranson. "Then you admit killing Haller?" he demanded. "Yes." Ranson nodded sombrely. "In the struggle. Self-defense. But even if it hadn't been self-defense, I probably would have fought with him. That music was madness, I tell you! Madness! Nobody's responsible when under its influence! I...." "You killed Haller," Captain Maxwell said. "And you blame it on this alleged music. I might believe you, Ranson, but how many other people would? Even members of Terrestial Intelligence aren't sacro sanct. I'll track down whoever was outside Haller's house, you can...." motioned to the two gray-uniformed patrolmen. "Take Mr. Ranson." And then Steve Ranson went into action. In one blinding burst of "No good. Got to work fast." Ranson backed toward the door, gun Ranson took the key from the massive plastic door as he backed halted him, but a wave of Ranson's T.I. card put the man aside. Free of headquarters, Ranson began to run. Only a few moments, he pursuit. Like a lean gray shadow Ranson ran, twisting, dodging, among Ranson stood motionless for a moment as a canal boat swept by, then Ranson touched a lever and a tiny electric motor in the head of the Ranson tapped the cane carefully upon the ground, avoiding those places Ranson now carried. it. Ranson tried the door, found it locked. A quick spurt from his flame-gun melted the lock light jetted through a half-open door. Ranson moved toward it, silent black fluid did not so much as waver at Ranson's entrance. Ranson gasped. The bizarre figure was that of Dr. Elath Taen, at Ranson. Quick as he was, the T.I. man was quicker. A spurt of flame leapt from his gun, shattering the tube. The dark liquid hissed, smoking, on to the floor. "Well done, Mr. Ranson." Elath Taen nodded calmly. "Had the acid struck "That's about enough of your tricks!" Ranson grated. "Come along, Dr. "Quit stalling!" Ranson snapped. "Get going! I...." The words faded on "Good God!" Ranson's eyes darted about the laboratory. "That ... that's the same as Haller and I...." "Exactly, Mr. Ranson." Elath Taen smiled thinly. "Listen!" "Come ... come on," Ranson said thickly. "Got to get out of here." Across the laboratory Elath Taen had slumped to the floor, a vague smile of triumph on his face. Ranson turned to the direction of the music, tried to raise his gun, but the weapon slipped from his fingers, he fell to his knees. Sleep ... that was all that mattered ...

<question>:
How did Ranson kill Haller?

<options>:
A He shot him with Haller's own gun.
B He choked him to death.
C He used his agency-assigned flame-gun to kill Haller.
D He broke Haller's arm, and Haller hit his head while falling.

<answer>:

A