2. Let the altitudes of $\triangle A B C$ be $A D, B E, C F$, and let the orthocenter $H$ not coincide with any vertex, then the number of circles that can be determined by some four points among $A, B, C, D, E, F, H$ is ( ).
(A) 3
(B) 4
(C) 5
(D) 6
2. D.

As shown in the figure, the following sets of four points are concyclic:
$$
A F H E, B F H D, C D H E, A F D C, B F E C, C D F A \text {. }
$$

If $\triangle A B C$ is an obtuse triangle, the same conclusion applies.