A)The class thought the demonstration was too complex.
B)Too many students showed up.
C)The professor didn’t show up.
D)The professor cancelled it.
原文：
W: Why didn’t you have your geology class today?
M: Only three out of a class of twenty-five showed up. Since the professor had planned to present a complex demonstration, he decided to cancel the class until everybody could be present.
Q: why didn’t the geology class meet today?