The rest mass of the deuteron,${}_1^2H$,is equivalent to an energy of $1876 \, MeV$. The rest mass of a proton is equivalent to $939 \, MeV$ and that of a neutron is $940 \, MeV$. $A$ deuteron may disintegrate into a proton and a neutron if it:

• A
  emits a $\gamma$-ray photon of energy $2 \, MeV$
• B
  captures a $\gamma$-ray photon of energy $2 \, MeV$
• C
  emits a $\gamma$-ray photon of energy $3 \, MeV$
• D
  captures a $\gamma$-ray photon of energy $3 \, MeV$