 Hello and welcome to the session. Let us discuss the following question. Question says, if A and B are events such that probability of A upon B is equal to probability of B upon A, then A is a subset of B, but A is not equal to B. This is the option A. Option B is A is equal to B. Question says, A intersection B is equal to 5. Option D is probability of A is equal to probability of B. We have to choose the correct answer from A, B, C and D. Let us now start with the solution. Now we are given probability of A upon B is equal to probability of B upon A. We know probability of A when B has occurred is equal to probability of A intersection B upon probability of B. Similarly, probability of B when A has occurred is equal to probability of B intersection A upon probability of A. Now probability of A upon B is equal to probability of B upon A implies probability of A intersection B upon probability of B is equal to probability of B intersection A upon probability of A. Now we know that probability of A intersection B is equal to probability of B intersection A. Now let us name this expression as expression 1 and this expression as expression 2. Now substituting 2 in 1 we get probability of A intersection B upon probability of B is equal to probability of A intersection B upon probability of A. Now dividing both the sides of this expression by probability of A intersection B we get 1 upon probability of B is equal to 1 upon probability of A. Now taking reciprocal of both the sides we get probability of B is equal to probability of A. So our correct answer is D. So this is our required answer. This completes the session. Let me understood the solution. Take care and have a nice day.