The owner of a pizza shop observes that when she raises the price of a large pizza, her total revenue decreases, and when she lowers the price of a large pizza, her total revenue increases. This suggests that:

A、pizza lovers act irrationally.;

B、the demand for her large pizzas is elastic with respect to price.;

C、the demand for her large pizzas is inelastic with respect to price.;

D、there are few good substitutes for a large pizza.