`.^90 Sr` from the radioactive fall out from nuclear bomb ends up in the bones of human being through the milk consumed by them. It causes impairment of the production of res blood cells.
The energetics `beta-`particles emitted in the decay of `.^90 Sr` damage the bone marrow.

Options

A. (a) both assertion and reason are ture and reason is the correct explanation of assertion
B. (b) If both assertion and reason are true but reason is not the correct explanation of assertion
C. (c) If assertion is true but reason is false
D. (d) If both assertion and reson are false.

Answer

A