GKFix MCQ Question

How much work is required to bring the fourth charge (-q) to point D?

• A. +\frac{q^2}{4\pi\epsilon_0 d} \left(2 - \frac{1}{\sqrt{2}}\right)
• B. -\frac{q^2}{4\pi\epsilon_0 d} \left(2 - \frac{1}{\sqrt{2}}\right)
• C. \frac{q^2}{4\pi\epsilon_0 d} \left(1 - \frac{2}{\sqrt{2}}\right)
• D. Zero