A Space Probe Approaches a Planet, Taking Measurements as It $6000 \mathrm { MV }$

Multiple Choice

A space probe approaches a planet, taking measurements as it goes. If it detects a potential difference of $6000 \mathrm { MV }$ between the altitudes of $253,000 \mathrm {~km}$ and $276,000 \mathrm {~km}$ above the planet's surface, what is the approximate electric field strength produced by the planet at $264,500 \mathrm {~km}$ above the surface? Assume the electric field strength is approximately constant at these altitudes.

A) $493 \mu \mathrm { N } / \mathrm { C }$
B) $0.261 \mathrm {~N} / \mathrm { C }$
C) $561 \mathrm {~N} / \mathrm { C }$
D) $261 \mathrm {~N} / \mathrm { C }$