At what distance $($if any$)$ would two electrons need to be placed in order for the net contribution of their, repulsive electric forces, and attractive gravity forces, to cancel out?

Remember:

$F_G=\frac{G{m}_1{m}_1}{r^2},$ where $G=6\mathrm{.}67{10}^{-11}N\frac{m^2}{k{g}^2}$

$r=1\mathrm{.}35{10}^{20}m$

$r=7\mathrm{.}4x{10}^{-21}m$

$r=8\mathrm{.}61x{10}^{-11}m$

$r=1\mathrm{.}16{10}^{16}m$

None of the above