In Terms of Increasing Penetrating Ability, the Three Kinds of Rays

Multiple Choice

In terms of increasing penetrating ability, the three kinds of rays emitted by radioactive isotopes are

A) $\alpha , \beta , \gamma$
B) $\beta , \gamma , \alpha$
C) $\gamma , \alpha , \beta$
D) $\beta , \alpha , \gamma$
E) All have the same penetrating ability.