To the Gilded Age farmer, the worst problem was a. over production and overpricing of farm produce b. over production and under pricing of farm goods c. inflation d. all the above.
Of the options that you have given us, the only possible answer is B. This was a major problem that helped to cause farmers to want to create things like the Grange.
A cannot be right because overpricing of products is not likely to be a problem for a producer. C cannot be right because farmers actually wanted inflation. They wanted the government to weaken the dollar by allowing the coinage of silver. This would have made it easier for them to pay off their debts. Given that A and C are wrong, D must also be wrong.
Overproduction and underpricing was a real problem. Low prices for farm products means farmers can't make much money. This makes it hard for them to pay off debts and make a living. Therefore, B is the right answer.