Only after they had discussed the matter for several hours _____ a decision. [ ]

A. they reached

B. did they reach

C. they reach

D. do they reach

中国婚礼中有一个隆重的“拜堂”仪式，新郎、新娘在鞠躬时他们的腰应该弯到多少度是最合适的，其中三拜分别是拜什么？