Why are hamburgers so popular in AmericaA．Because

单项选择题

Questions 14-17 are based on the following monologue introducing the origin of the expression "Where is the beef".

Why are hamburgers so popular in America

A．Because they are made from beef.
B．Because they are cheaper than any other kind of food.
C．Because they are served quickly at a low price.
D．Because hamburger is the only fast food in America.