How Far from a Lens Having a Focal Length Of $+ 50 \mathrm {~mm}$

Multiple Choice

How far from a lens having a focal length of $+ 50 \mathrm {~mm}$ must the object be placed if it is to form a virtual image that is $3.0$ times the size of the object?

A) $33 \mathrm {~mm}$
B) $54 \mathrm {~mm}$
C) $42 \mathrm {~mm}$
D) $48 \mathrm {~mm}$