The price of coffee fell sharply last month, while the quantity sold remained the same. Five people suggest various explanations:

Van: Demand decreased, but it was perfectly inelastic.

Amy: Demand decreased, but supply was perfectly inelastic.

Carlos: Demand decreased, but supply increased at the same time.

Deborah: Supply increased, but demand was perfectly inelastic.

Felix: Supply increased, but demand was unit elastic.

Who could possibly be right? Check all that apply.

Van

Amy

Carlos

Deborah

Felix