In the football match between two classes, there are several ways to decide who will kick off first. () The rules are unfair. Decide by flipping a coin. B. It is decided by "stone"

A, because a coin has only two sides, the possibility of positive and negative is 50%, so it is fair;

B, the decision of "rock, scissors and cloth" is fair because the probability of winning or losing is one third;

C. Dice: open first if it is greater than 3, and then open if it is less than 3 (the numbers on the dice are 1, 2, 3, 4, 5, 6). There are three numbers greater than 3, and two numbers less than 3 are 1 2, so it is unfair.

So choose: C.