【单选题】Space is a dangerous place, not only because of meteors(流星) but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on earth. Light gets through, and...
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