When the mother heard a bomb exploded _____ his son was working, her heart _______, wondering if

her son was safe.      [ ]

A. where; sank  

B. in which ; broke  

C. that; was broken    

D. at which; sank

会社名が変わるのを________社員の制服も新しくすることが決められた。

A．めぐって

B．越えて

C．おいて

D．契機に