Divide the participating 10 teams into two groups, A and B, with 5 teams in each group. The probability that Team A and Team B are just in Group A is (

From the meaning of the problem, we know that the problem is the probability of an equal possible event.

∫ All the events involved in the experiment are the result of dividing the team of 10 into two groups and using C 105C555.

The eligible event is that Team A and Team B happen to be in Group A, and then three teams can be selected from the other eight teams. * * * C 8 3 C 5 5 has five results.

∴P= C 38 C 55 C 5 10 C 55 = 2 9。

So choose C.