A Camera Used for Aerial Mapping Has a Lens with a 30-Cm

Multiple Choice

A camera used for aerial mapping has a lens with a 30-cm diameter maximum aperture and a 42-cm focal length. Light of 550 nm wavelength is used to form the image. Assuming that the
Resolution of the camera is limited only by diffraction, what is the smallest angle (in milliradians)
Subtended by an object on the ground that can be resolved by this camera at maximum aperture?

A) 6.3 mrad
B) 1.6 mrad
C) 4.5 mrad
D) 2.2 mrad
E) 3.2 mrad