She is a vegetarian. She will if you mention eating meat in front of her.A. fall over the

问题补充：

She is a vegetarian. She will if you mention eating meat in front of her.

A. fall over the moon

B. be down in the dumps

C. get hot under the collar

D. laugh her head off

答案：

A. fall over the moon

B. be down in the dumps

(答案→)C. get hot under the collar

D. laugh her head off

解析：句子理解，四个选项分别表示非常兴奋、垂头丧气、怒气冲天和笑掉大牙，根据题意他是个素食主义者。如果你在她面前提到吃肉她会怒气冲天。选C。