`A B C` is a right-angled triangle in which `/_B=90^0` and `B C=adot` If `n` points `L_1, L_2, ,L_nonA B` is divided in `n+1` equal parts and `L_1M_1, L_2M_2, ,L_n M_n` are line segments parallel to `B Ca n dM_1, M_2, ,M_n` are on `A C ,` then the sum of the lengths of `L_1M_1, L_2M_2, ,L_n M_n` is `(a(n+1))/2` b. `(a(n-1))/2` c. `(a n)/2` d. none of these