— What did the head teacher think of what you had done?

— He was happy _____ it. [ ]

A. to

B. with

C. at

D. by

某甲与某乙有仇，遂寻机报复。一天，某甲得知某乙一人在家，便携匕首向乙家走去，途中突然腹痛，只得返回家中。某甲的行为属于（）。

A．犯罪中止

B．犯罪预备

C．犯罪表示

D．不构成犯罪