According to the combination of prime factors, it is obvious that 96 can only be a score, not an age and ranking, so the score is 96, ranking third;

Then the age of the fifth grade in primary school is probably 1 1- 13 years old, so it is only possible to exclude 2×2×2×2, 3×3, 3×3×2 years old;

A: Xiaoming's age is 12 years old, ranking third with 96 points.

So the answer is: 12.