Which one of the following statements is accurate?
a. the green revolution was instrumental in the increase of the world's food supply.
b. agriculture has been challenged by the use of selective breeding.
c. wheat, corn, soybeans, and cabbage are the main four plants responsible for providing food to people in the world.
d. gymnosperms provide humans with the most food.

Answer D is not correct, as gymnosprems are used widely for consumer goods such as lumber, soap, and nail polish. Answer C is not correct event though wheat and corn are two of the main foods supplied to people in the world. Answer B is a very subjective question, because some people argue that selective breeding helps agriculture, while others do not. The correct answer is A. The green revolution was a period of scientific discoveries that lead to an increase in the supply of food worldwide.