1. Given $\alpha \in\left(0, \frac{\pi}{4}\right), t_{1}=(\tan \alpha)^{\tan \alpha}, t_{2}=(\tan \alpha)^{\omega \cos \alpha}, t_{3}=(\cot \alpha)^{\sin \alpha}, t_{4}=$ $(\cot \alpha)^{\infty \pi a}$. Then the size relationship of $t_{1}, t_{2}, t_{3}, t_{4}$ is () .
A. $t_{1}<t_{2}<t_{3}<t_{4}$
B. $t_{2}<t_{1}<t_{3}<t_{+}$
C. $t_{1}<t_{3}<t_{4}<t_{2}$
U. Cannot be determined
1. $\mathrm{B}$

Since $\alpha \in\left(0, \frac{\pi}{4}\right)$,
we have $0<\tan \alpha<1<\cot \alpha$.
Therefore, $(\tan \alpha)^{\tan \alpha}<(\cot \alpha)^{\tan \alpha}$.
$(\cot \alpha)^{\cot \alpha}<(\cot \alpha)^{\cot \alpha}$
$(\tan \alpha)^{\cot \alpha}<(\tan \alpha)^{\tan \alpha}$
Thus, $(\tan \alpha)^{\cot \alpha}<(\tan \alpha)^{\tan \alpha}<(\cot \alpha)^{\tan \alpha}<(\cot \alpha)^{\cot \alpha}$.
Hence $t_{2}<t_{1}<t_{3}<t_{4}$.