a b c d

a

$\text{Debroglie wavelength }\lambda = \frac{h}{p}$ $ \text{If Debroglie wavelength of two particles are equal then momentum of the two particles are also equal.}$ $\Rightarrow P_\alpha = P_p$ $\Rightarrow m_\alpha v_\alpha = m_p v_p$ $\Rightarrow \frac{v_p}{v_\alpha} = \frac{m_\alpha}{m_p} = 4$