Suppose Your Telescope Has Perfect Mirrors and Is Limited Only $400 \mathrm {~nm}$

Multiple Choice

Suppose your telescope has perfect mirrors and is limited only by diffraction. If you are viewing with light of $400 \mathrm {~nm}$ wavelength, what diameter mirror in a space telescope would have $1.0 - \mathrm { km }$ resolution of objects on Mars when viewed from above the earth at a time when the Earth-Mars distance of 80 million kilometers?

A) $390 \mathrm {~m}$
B) $39 \mathrm {~km}$
C) $3.9 \mathrm {~m}$
D) $3.9 \mathrm {~km}$
E) $39 \mathrm {~m}$