The harm radiation has done to the Apollo crew members ______. ( )

A．exposure to even tiny amounts of radiation is fatal
B．the effect of exposure to radiation is slow in coming
C．radiation is avoidable in space exploration
D．astronauts in spacesuits needn't worry about radiation damage

A．the Apollo mission was very successful
B．protection from space radiation is no easy job
C．astronauts will have deformed children of grandchildren
D．radiation is not a threat to well protection space explorers