The correct answer is - D. increased crop diversification.
By increasing the crop diversification there will be no problems in causing widespread, or any type of famine whatsoever. In fact, this can be very beneficial, and can actually help with the expected problem in the near future. With bigger diversification of the crops, we will get new types of crops that will be more resilient to certain types of climates, or even pests, and they can be grown on places where they typically can not be grown with their original genetics.