Two events are termed to be mutually exclusive if they cannot happen at the same time. This means that the probability of occurring at the same time is zero.
A is correct.
The probability of the two events happening at the same time is zero
B is incorrect
The probability of both happening at the same is not equal to the probability of B alone
C is incorrect
The probability of the union of the two is never equal to zero since they might occur at different times
D. Is incorrect
The probability of both happening at the same time is never equal to the probability of A alone
