A University Observes That When It Raises the Price of Hockey

A university observes that when it raises the price of hockey tickets,total revenue from hockey games increases and when it lowers the ticket price,total revenue falls.This suggests that

A) hockey fans act irrationally.
B) the demand for tickets to hockey games must be elastic.
C) there are many good substitutes for university hockey games.
D) the demand for tickets to hockey games must be inelastic.
E) the demand for tickets to hockey games must be unit-elastic.