Today just as technology changed the face of industry, farmers have undergone an "agricultural revolution". On the farm of today, machines provide all the power. One of the most important benefits will be the farm computer. A few forward-looking farmers are already using computers to help them run their farms more efficiently. The computers help them keep more accurate records so they can make better decisions on what crops to plant, how much livestock to buy, when to sell their products, and how much profit they can expect. Many computer companies have been developing special computer programs just for farmers. Programs are being written for hog  producers, grain farmers, potato farmers, and dairy farmers. In the future, farmers will be able to purchase computer programs made to their needs. Because of the growing importance of computers on the farm, students at agricultural colleges are required to take computer classes in addition to their normal agricultural courses. There can be no doubt that farmers will rely on computers even more in the future. While the old-time farm depended on horse power, and modern farms depend on machine power, farms of the future will depend on computer power. Another technological advance which is still in the experimental stage is the robot, a real "mechanized hired hand" that will be able to move and, in some ways, think like a human being. Unlike farmers of the present, farmers of the future will find that many day-to-day tasks will be done for them. Scientists are now developing robots that will be able to shear  sheep, drive tractors, and harvest fruit. Even complex jobs will be done by robots. For example, in order to milk their cows, farmers must first drive them into the special barn , then connect them to the milking machines, watch the machines, and disconnect them when they are finished. In the future, this will all be done by robots. In addition, when the milking is completed, the robots will automatically check to make sure that the milk is pure. The complete mobilization of the farm is far in the future, but engineers expect that some robots will be used before long. Which sentence carries the main idea of the whole passage?
The first sentence of the first paragraph. The first sentence of the second paragraph. The first sentence of the third paragraph. The last sentence of the second paragraph.