In the given circuit the power dissipated through resistance `R_(1) = 9 Omega` is `P_(1)`, when switch `S_(1)` is closed and `S_(2)` is opened and the power dissipated through resistance `R_(2) = 4 Omega` is `P_(2)`, when switch `S_(2)` is closed and `S_(1)` is opened. If `P_(1) = P_(2)`, then r is equl to :
A. `2 Omega`
B. `6 Omega`
C. `4 Omega`
D. `3 Omega`
