An astronaut is doing a spacewalk on a long tether from the International Space Station (mass of 420,000 kg). His spacesuit includes a very sensitive gravitometer, which indicates the gravitational force acting on the astronaut and his spacesuit from the ISS is 7.0 E−7 N. If the mass of the astronaut in his suit is 250 kg, how far away from the ISS is the astronaut if G = 6.67 E−11 N*m2/kg2?

A. 0.100 km
B. 0.200 km
C. 0.500 km
D. 1 km