The Above Figure Illustrates the Market for Corn

The above figure illustrates the market for corn. If point 'a' represents the original equilibrium and point 'b' the new equilibrium, which of the following could have caused the change?

A) An increase in the number of corn growers.
B) An increase in the cost of the fertiliser used to grow the corn.
C) An increase in the price of wheat, a substitute in production for corn.
D) An increase in income if corn is a normal good.
E) A belief among corn farmers that the price of a tonne of corn will be higher next month.