The total binding energies of \( ^{15}O \), \( ^{16}O \), and \( ^{17}O \) are 111.96 MeV, 127.62 MeV, and 131.76 MeV, respectively. Determine the energy gap between the \( 1p_{1/2} \) and \( 1d_{1/2} \) neutron shells for nuclei with mass numbers close to 16.
1
\( 4.1 \, \text{MeV} \)
2
\( 11.5 \, \text{MeV} \)
3
\( 15.7 \, \text{MeV} \)
4
\( 19.8 \, \text{MeV} \)