3. If $A, B, C$ are the three interior angles of $\triangle ABC$, and $A<B<C .\left(C \neq \frac{\pi}{2}\right)$, then which of the following conclusions is correct?
A. $\sin A<\sin C$
B. $\cot A<\cot C$
C. $\tan A<\tan C$
D. $\cos A<\cos C$
3. A $A<C \Rightarrow a<c \Rightarrow 2 R \sin A<2 R \sin C \Rightarrow \sin A<\sin C$