[单选题]
A plano-convex lens is to have a foca hjk08gqif sh0:kceb zdf8-9*l len ca g;(lw9 bqh2.tnleos:;f.z f /he5sgth of 40 cm. It is made of glass of b9lc2n:h qa(/fwol.t s ;h ge5e.fz;sindex of refraction 1.65. What radius of curvature is required?
A. $13 \; cm$
B. $26 \; cm$
C. $32 \; cm$
D. $36 \; cm$
