What, Approximately, Are the Dimensions of the Smallest Object on Earth

Multiple Choice

What, approximately, are the dimensions of the smallest object on Earth that the astronauts can resolve by eye at 200 km height from the space shuttle? Assume λ = 500 nm light and a pupil diameter D = 0.50 cm. Assume eye fluid has an average n = 1.33.

A) 150 m
B) 100 m
C) 250 m
D) 25 m
E) 18 m