单项选择题

W:Excuse me.
M:Yes
W:I bought this calculator here yesterday but it doesn’t work.
M:Oh, let’s see what’s wrong.
W:This button doesn’t work.When I push it nothing happens.
M:You are right. I’ll give you another one. Show me your receipt please.

What do we learn from the conversation()

A. Nothing is wrong with the calculator
B. The calculator is too expensive
C. The button of the calculator is off
D. To change a new calculator, the receipt is needed