Two Particles with Charges Q and -Q Are Fixed at the Vertices

Multiple Choice

Two particles with charges Q and -Q are fixed at the vertices of an equilateral triangle with sides of length a. If k = 1/4 $\pi$$\varepsilon$ ₀, the work required to move a particle with a charge q from the other vertex to the center of the line joining the fixed charges is:

A) 0
B) kQq/a
C) kQq/a²
D) 2kQq/a
E)