Probability of lottery sequence

What A and B say is wrong, and what C says is right. (2 points)

Let's draw lots first.

Draw a tree diagram

(6 points)

It can be seen from the tree diagram that there are six possible results, among which there are two cases where B and C draw the symbol A, and the probability is 13. Similarly, no matter who draws lots first, the probability of their three schools winning the A sign is 13.

Therefore, C's statement is correct. (9 points)