Containers A, A and B respectively represent two pairs of homologous chromosomes during meiosis of animals, and A is wrong;

B, the color and letters of the ball indicate the type of allele, and B is wrong;

C, this experiment simulates the free combination of non-allelic genes on non-homologous chromosomes during meiosis, and C is correct;

D, the number of two kinds of balls in each container should be equal, and the total number of balls in two containers should be equal. D is wrong.

So choose: C.