2. On two non-perpendicular skew lines $a, b$, there are 4 different points $A, B, C, D$, where $A \in a, B \in a, C \in b, D \in b$. For the following two propositions:
(1) The lines $A C$ and $B D$ are always skew lines;
(2) The points $A, B, C, D$ can never be the 4 vertices of a regular tetrahedron.
Which of the following propositions is correct?
A. (1)
B. (2)
C. (1)(2)
D. Neither (1) nor (2) is correct
2. C
(1) Correct. If the lines $A C$ and $B D$ are not skew lines, then points $A, B, C, D$ are coplanar, which implies that $A B$ and $C D$ are not skew lines, contradicting the given condition.
(2) Correct. If the tetrahedron $A B C D$ is a regular tetrahedron and the opposite edges $A B$ and $C D$ are perpendicular, this contradicts the given condition that the skew lines $a, b$ are not perpendicular.