The following figure represents two biconvex lenses \( L_1 \) and \( L_2 \) having focal length \( 10 \, \text{cm} \) and \( 15 \, \text{cm} \) respectively. The distance between \( L_1 \) and \( L_2 \) is:
\( 25 \, \text{cm} \)
\( 15 \, \text{cm} \)
\( 35 \, \text{cm} \)
\( 10 \, \text{cm} \)