單項(xiàng)選擇題根據(jù)《電離輻射防護(hù)和輻射源安全基本標(biāo)準(zhǔn)》,職業(yè)照射一年中晶體所受的當(dāng)量劑量不應(yīng)超過

A.20mSv
B.50mSv
C.150mSv
D.200mSv
E.500mSv