[单选题]
How far from a lens of focal lengtas :ubjv5l hn+k;:zuphzz-73 h 50 mm must thdd ))sq w4e;pmc5a k-lk aif:5e object be placed if it is to form a virtual image magnified in size by a factor of theaa-i4kpckqs dl)f;5 m5):wd ree?
A. $33 \; mm$
B. $42 \; mm$
C. $48 \; mm$
D. $54 \; mm$
