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

<passage>:
"It seems nobody's told the Aga Kagans about fiscal years," Retief said. "They're going right ahead with their program of land-grabbing on Flamme. So far, I've persuaded the Boyars that this is a matter for the Corps, and not to take matters into their own hands." foothold against Neo-Concordiatist elements was deemed desirable. Now the situation has changed." "The Boyars have spent sixty years terraforming Flamme," Retief said. "They've cleared jungle, descummed the seas, irrigated deserts, set out forests. They've just about reached the point where they can begin to enjoy it. The Aga Kagans have picked this as a good time to move in. They've landed thirty detachments of 'fishermen'—complete with armored trawlers mounting 40 mm infinite repeaters—and another two dozen parties of 'homesteaders'—all male and toting rocket launchers." "Surely there's land enough on the world to afford space to both anti-Concordiatist enclave. The Aga Kagans didn't want to play, either. But now that the world is tamed, they're moving in." "The exigencies of diplomacy require a flexible policy—" "I want a firm assurance of Corps support to take back to Flamme," diplomatic triple-speak. They just want to hold onto the homes they've made out of a wasteland." like a dinosaur hunt." "When you get there," said Magnan, "I hope you'll make it quite clear gorgeous blaze of vermillion and purple that reflected from a still lake, tinged the broad lawn with color, silhouetted tall poplars among flower beds. "You've done great things here in sixty years, Georges," said Retief. "Not that natural geological processes wouldn't have produced the same results, given a couple of hundred million years." "Don't belabor the point," the Boyar Chef d'Regime said. "Since we seem to be on the verge of losing it." "So what are we going to do? Sit here and watch these goat-herders take over our farms and fisheries?" "Those goat-herders aren't all they seem. They've got a first-class "The 'goat-skin' tents are a high-polymer plastic, made in the same factory that turns out those long flowing bullet-proof robes you mention. The animals are just for show. Back home they use helis and ground cars of the most modern design." "Something to do with internal policies, I suppose." "So we sit tight and watch 'em take our world away from us. That's what these monkeys as soon as they set foot on our world." "Slow down, I haven't finished yet. There's still the Note." "I've got plenty of paper already. Rolls and rolls of it." "Give diplomatic processes a chance," said Retief. "The Note hasn't what we run into, here's how we'll play it...." II Eight miles into the rolling granite hills west of the capital, a Slumped in the padded seat, the Boyar Chef d'Regime waved his cigar glumly at the surrounding hills. "Fifty years ago this was bare rock," he said. "We've bred special strains of bacteria here to break down the formations into soil, and we followed up with a program of broad-spectrum fertilization. We planned to put the whole area into crops by next year. Now it looks like the goats will get it." "Will that scrubland support a crop?" Retief said, eyeing the lichen-covered knolls. "Sure. We start with legumes and follow up with cereals. Wait until you see this next section. It's an old flood plain, came into production thirty years ago. One of our finest—" grain, cutting three narrow swaths that ran in a straight sweep from the ridge to the air-car where Retief and the Chef d'Regime hovered, waiting. "May the creatures dine well ere they move on." "Hah! The goats of the Aga Kaga graze on the lands of the Aga Kaga." "Just stick to the plan," Retief said. "And remember: a handful of luck is better than a camel-load of learning." The air car followed the escort down a long slope to a dry river bed and across it, through a barren stretch of shifting sand to a green oasis set with canopies. The armed escort motioned the car to a halt before an immense tent of "Planetary government?" The Aga Kaga spat grape seeds on the rug. "My men have observed a few squatters along the shore. If they're in distress, I'll see about a distribution of goat-meat." Jelebi," the Aga Kaga said. "I know a few old sayings myself. For example, 'A Bedouin is only cheated once.'" "We have no such intentions, Excellency," Retief said. "Is it not "Now," the Aga Kaga said. "Let's drop the wisdom of the ages and get down to the issues. Not that I don't admire your repertoire of as you point out, small wisdom to small minds. I'm here to effect a settlement of certain differences between yourself and the planetary "Yes, yes. Skip the titles." Retief flipped over two pages. "... and with reference to the recent relocation of persons under the jurisdiction of his Excellency, has the honor to point out that the territories now under settlement comprise a portion of that area, hereinafter designated as Sub-sector Alpha, which, under terms of Flamme—" "Come to the point," the Aga Kaga cut in. "You're here to lodge a complaint that I'm invading territories to which someone else lays of my government. They're still gnawing their beards and kicking themselves because their ancestors dropped science in favor of alchemy and got themselves stranded in a cultural dead end. This charade is supposed to prove they were right all along. However, I've no time rest, your pious views about the virtues of hard labor are as childish as my advisors' faith in the advantages of primitive plumbing. As for myself, I am a realist. If two monkeys want the same banana, in the end an activity carried on only by those who have inherited the mantle of Colonial Imperialism." realities of popular folk-lore. Let's be pragmatic it's a matter of historical association. Some people can grab land and pass it off lightly as a moral duty others are dubbed imperialist merely for "It's pointless to resist," he said. "We have you outgunned and outmanned. Your small nation has no chance against us. But we're prepared to be generous. You may continue to occupy such areas as we do not immediately require until such time as you're able to make other arrangements." "And by the time we've got a crop growing out of what was bare rock, you'll be ready to move in," the Boyar Chef d'Regime snapped. "But you'll find that we aren't alone!" It has been the fate of your spiritual forebears to carve civilization from the wilderness and then, amid tearing of garments and the heaping of ashes of self-accusation on your own confused heads, to withdraw, leaving the spoils for local political opportunists and mob leaders, clothed in the mystical virtue of native birth. Have a banana." The Aga Kaga nodded thoughtfully. "What are you getting at?" "You're basing your plan of action on the certainty that the Corps will sit by, wringing its hands, while you embark on a career of planetary piracy." "Isn't it the custom?" the Aga Kaga smiled complacently.

<question>:
How does the terraforming technology work?

<options>:
A It instantly transforms bare planets into planets that can support life
B It infects organisms on the planet with a virus that changes their DNA to make them more suitable for human consumption
C It can only work on land that has previously contained life
D It follows ecological processes to slowly transform barren land into arable land over time

<answer>:

D