In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of the image is I. The magnification of the telescope is :

Question

( A ) $\frac{L}{I}$
( B ) $\frac{L}{I} +1$
( C ) $\frac{L}{I} -1$
( D ) $\frac{L+I}{L - I}$