The de Broglie wavelength associated with an electron accelerated through a potential difference $V$ is $\lambda_e$ and the de Broglie wavelength associated with a proton accelerated through the same potential difference is $\lambda_p$. If their corresponding masses are $m_e$ and $m_p$, respectively, then the ratio of their de Broglie wavelengths is . . . . . . .

• A
  $\sqrt{\frac{m_p}{m_e}}$
• B
  $\sqrt{\frac{m_e}{m_p}}$
• C
  $\frac{m_p}{m_e}$
• D
  $(\frac{m_p}{m_e})^2$