 Hello and welcome to the session. Let us discuss the following question. Question says, if B A is equal to 1 upon 2 or we can say if the probability of A is equal to 1 upon 2, probability of B is equal to 0, then probability of A upon B is A 0 B 1 upon 2 C not defined D 1. We have to choose the correct answer from A, B, C and D. Let us now start with the solution. Now we know that conditional probability of A when B has occurred is equal to probability of A intersection B upon probability of B. Now we have given that probability of B is equal to 0 below this expression is defined only when probability of B is not equal to 0. Now probability of B is equal to 0 implies that probability of A upon B is not defined. So our correct answer is C. So this is our required answer. This completes the session. Hope you understood the solution. Take care and have a nice day.