The idea of his wife ______up in the case upset him so much

The idea of his wife ______up in the case upset him so much that he stayed awake al night.
The idea of his wife ______up in the case upset him so much that he
stayed awake al night.
A.mixed b mixing c being mixed D to be
mixed
问了好多个人.都没有答出来.希望你能解答.