The intersection of two sets is the set of elements that are common to both sets. In this case, Set A = {5, 6, 7, 8} and Set B = {7, 8, 9, 10}. Therefore, the intersection of Set A and Set B is {7, 8}.
Therefore, the number that is in the intersection of sets A and B is D: 7
It's important to note that both numbers 7 and 8 are in the intersection of the sets, but the question is asking for only one number.