Describe the condition under which the statement an b = b would be true? Give an example

Question

I'm just really stuck on this question so it would help if someone could guide me through it, and to get to the right answer.

Answer 1

b=b is a tautology, an identity a statement which is always true, for any b. b can be any number or any object or anything, and b=b is still true.

The probability that b = b is true is 100%