All games -because of the rainstorm ,many students could do

All games _because of the rainstorm ,many students could do nothing but study in the classroom
A were canceled B having been canceled C had been canceled D have been canceled
Ps:我自己比较矛盾的是B和C ,B是现在分词的完成被动式我觉得就是充当非谓语,但是前半个分句没有谓语哪来非谓语呢 请详尽说明
我已经知道答案是B了 我想要的是解析