为了保障人体安全，避免人体与危险源（如机械转动部位等）直接触所需要的空间称为（）。

A.作业活动空间

B.作业接触空间

C.安全防护空间

D.作业休息空间

When magnesium sulfate is administered to a client in labor, its action occurs at which of the following sites

A. Neural-muscular junctions.
B. Distal renal tubules.
C. Central nervous system (CNS).
D. Myocardial fibers.