`.^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. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If the assertion and reason both are false

Answer

A

Explanation

`""_(38)^(9)Sr` decays to `""_(39)^(90)Y` by the emission of `beta`- rays. Sr gets absorbed in bones along with calcium. Reason is also true. `""^(90)Sr overset(beta)rarr ""^(9)Y` emits `beta`- rays of very high energy. It does not emit `gamma`- rays. The damage is by the `beta`- rays only.