Calculate the Work Done to Bring a Charge, Q = $\sigma$

Multiple Choice

Calculate the work done to bring a charge, Q = 1 mC, from infinity and place it at a distance R = 10 cm along the axis of a uniformly charged disk with surface charge density $\sigma$ = 10 $\mu$ C/m² and radius R.

A) 78.9 J
B) 23.4 J
C) 56.5 J
D) 97.8 J
E) zero