Answer
Choice (c)
Work Step by Step
The voltage is related to the electric field by
\begin{aligned}
& E=\frac{V}{l} \\
E &=\frac{6.0 \times 10^{6} \mathrm{V}}{12.0 \mathrm{m}} \\
E=& 5 \times 10^5 \mathrm{V} / \mathrm{m}
\end{aligned}
Hence, the answer is choice (c).
