The probabilities that three students Subhas, Monisha and Satabdi can solve a problem independently are p, q and r respectively.
The chance that exactly two of the three students solve the problem is -

Options

A. `pq(1-r)+qr(1-p)+rp(1-q)`
B. `pq+qr+rp`
C. `p(1-q)(1-r)+q(1-r)(1-p)+r(1-p)(1-q)`
D. none of these

Answer

A