Potential Energy of Point-Charges: an Electron Is Released from Rest

Multiple Choice

Potential energy of point-charges: An electron is released from rest at a distance of 9.00 cm from a proton. If the proton is held in place, how fast will the electron be moving when it is 3.00 cm from the proton? (m_el = 9.11 × 10^-31 kg, e = 1.60 × 10^-19 C, k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

A) 75.0 m/s
B) 106 m/s
C) 130 m/s
D) 1.06 × 10³ m/s
E) 4.64 × 10⁵ m/s