The pair having identical value of $\large\frac{e}{m}$:

Question

$\begin{array}{1 1}(a)\;\text{A proton and a neutron}\\(b)\;\text{A proton and a deuterium ion}\\(c)\;\text{An }\alpha-\text{Particle and a deuterium ion}\\(d)\;\text{An electron and } \gamma \text{-rays}\end{array}$