Define coulomb? Force experienced by option 1 coulomb charge placed at a distance of 1 m from a similar charge is

Question

$\begin{array}{1 1} (a)\;9 \times 10^{-9}\\ (b)\;9 \times 10^{-5}\\ (c)\;9 \times 10^{9} \\ (d)\;9 \times 10^{5} \end{array}$