Let be three independent events in a simple space. The probability that only B1 occur is , only B2 occur is , and only B3 occurs is . Let p be the probability that none of the events Bi occurs and these 4 probabilities satisfy the equations (All the probabilities are assumed to lie in the interval (0,1)). Then is equal to_____
Option: 1 2
Option: 2 3
Option: 3 5
Option: 4 6