Potential at center = Potential due to mass 1 + Potential due to mass 2

$\qquad= \large\frac{-Gm_1}{r_1}-\frac{Gm_2}{r_2}$

$\qquad= -6.67 \times 10 ^{-11} \bigg[ \large\frac{10^2}{5}+\frac{10^3}{5}\bigg]$

$\qquad= 1.47 \times 10^{-7} J/kg$

Hence d is the correct answer