The Objective and the Eyepiece of a Refracting Astronomical Telescope $320 \mathrm {~cm}$

Multiple Choice

The objective and the eyepiece of a refracting astronomical telescope have focal lengths of $320 \mathrm {~cm}$ and $4.0 \mathrm {~cm}$ , respectively. The telescope is used to view Neptune and the final image is set at infinity. The diameter of Neptune is $4.96 \times 10 ^ { 7 } \mathrm {~m}$ , and its distance from Earth at the time of observation is $4.4 \times 10 ^ { 12 } \mathrm {~m}$ . What is the angle (in milliradians) subtended by the final telescopic image of Neptune?

A) $1.1 \mathrm { mrad }$
B) $1.3 \mathrm { mrad }$
C) $1.5 \mathrm { mrad }$
D) $0.90 \mathrm { mrad }$
E) $1.7 \mathrm { mrad }$