Cardiac Pacemakers Once Used Plutonium-238 as a Power Source $\gamma$ Rays And

Cardiac pacemakers once used plutonium-238 as a power source.Plutonium-238 decays by the emission of $\gamma$ rays and $\alpha$ particles.This emission is not particularly harmful because

A) ( $\gamma$ rays are not absorbed very strongly by biological tissue, and α particles do not penetrate beyond the container.)
B) ( $\gamma$ rays and $\alpha$ particles are the least dangerous form of radiation.)
C) ( $\gamma$ rays and $\alpha$ particles do not penetrate beyond the container.)
D) ( $\gamma$ rays are absorbed by the container, and $\alpha$ particles do not affect biological tissue.)
E) ( $\beta$ - particles are the most harmful type of radiation, and 238Pu is not a $\beta$ - emitter.)