[单选题]
How far from a 50-mm foca ogl 3w3tbio7f3 -cy3w ;adjxk4 f2ap-wl)rz+ l length lens, such as is used in many 35-mm cameras, must an object be positioned if it is to form a real image magnified in size by ark;)adwz2 lja -fpx+4 factor of three?
A. $46 \; mm$
B. $52 \; mm$
C. $58 \; mm$
D. $67 \; mm$
