If `sin theta` and `cos theta` are the roots of the equation `lx^2 + mx + n = 0`, then (A) `l^2-m^2+2ln=0` (B) `l^2+m^2+2ln=0` (C) `l^2-m^2-2ln=0` (D) `l^2+m^2-2ln=0`