Two Electrons Are $20.0 \mathrm {~mm}$ Apart at Closest Approach

Multiple Choice

Two electrons are $20.0 \mathrm {~mm}$ apart at closest approach. What is the magnitude of the maximum electric force that they exert on each other? (e = 1.60 × 10^-19 C, k = 1/4??₀ = 9.0 10⁹ N ? m²/C²)

A) 5.8 × 10^-25 N
B) 2.3 × 10¹⁰ N
C) 2.3 N
D) 5.8 × 10^-27 N