2. Given $\alpha \in\left(0, \frac{\pi}{4}\right), t_{1}=(\tan \alpha)^{\tan \alpha}, t_{2}=$ $(\tan \alpha)^{\cot \alpha}, t_{3}=(\cot \alpha)^{\tan \alpha}, t_{4}=(\cot \alpha)^{\cot \alpha}$. Then the size relationship of $t_{1}, t_{2}, t_{3}, t_{4}$ is ( ).
(A) $t_{1}<t_{2}<t_{3}<t_{4}$
(B) $t_{2}<t_{1}<t_{3}<t_{4}$
(C) $t_{1}<t_{3}<t_{4}<t_{2}$
(D) cannot be determined
2. (B).
$$
\begin{array}{l}
\because \alpha \in\left(0, \frac{\pi}{4}\right), \\
\therefore 0<\tan \alpha<1<\cot \alpha . \\
\therefore(\tan \alpha)^{\tan \alpha}<(\cot \alpha)^{\tan \alpha}, \\
(\cot \alpha)^{\tan \alpha}<(\cot \alpha)^{\cot \alpha}, \\
(\tan \alpha)^{\cos \alpha}<(\tan \alpha)^{\tan \alpha} .
\end{array}
$$

Thus, $(\tan \alpha)^{\cot \alpha}<(\tan \alpha)^{\tan \alpha}<(\cot \alpha)^{\tan \alpha}$
$$
<(\cot \alpha)^{\cot \alpha} \text {. }
$$

Therefore, $t_{2}<t_{1}<t_{3}<t_{4}$.