[单选题]
A student constructs an astronomices8c54+izoq aal telescope with a magnification tn.:yn cw-pi a8- f*fo 32iwsrb3f(bfof 10. If the f tiwo(*a2 :pnbf cf-3sb8iwf3-y nr. telescope has a converging lens of focal length 50 cm, what is the focal length of the eyepiece?
A. $2.5 \; cm$
B. $5.0 \; cm$
C. $10 \; cm$
D. $25 \; cm$
