A is the graph average, 3 is the largest, followed by 1, and the smallest is 2, so it is unfair;

B, the graph is the average score, and the probability of each number is 1 4, so it is fair;

C, it is not average, so it is unfair;

The possibility of d, 1 is not equal to other possibilities, so it is unfair;

Therefore, choose: B.