[单选题]
An atomic nucleus has a c l59j7sd4q no5zksnuw0u u ,s*h-d jg1q(t) w:ds+lw ;khqw3cdarge of $+40e$. An electron is $10^{-9} \; m$ from the nucleus. What is the force on the electron?
A. $2.9 \; nN$
B. $1000 \; C$
C. $3.7 \; nN$
D. $6.8 \; nN$
E. $9.2 \; nN$