A Camera with a 20-Cm Diameter Lens Is Recording Images $$9.0 \times 10 ^ { 7 } \mathrm {~km}$$

A camera with a 20-cm diameter lens is recording images using a filter that allows only
light of wavelength 600 nm to pass through.
(a) What is the limit on the angular resolution (in microradians) in this case?
(b) What is the diameter of the minimum-sized features that could be resolved on Mars
with this camera? The distance to Mars at the time is 9 $$9.0 \times 10 ^ { 7 } \mathrm {~km}$$