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

项目经理在选调各娄人员，组成项目管理班子时，对（）中所有人员明确岗位责任制及其业务范围内承担的相应安全生产责任。

A.安全管理机构

B.施工管理体系

C.安全生产保证体系