Two identical small conducting balls B, and B, are given -7 pC and + 4 pC charges respectively. They are brought in contact with a third identical ball B3 and then separated. If the final charge on each ball is -2 pC, the initial charge on B was
(A) -2 pC
(С) -5 рС
(B) -3 рС
(D) -15 pC
