126 If $\varphi \in\left(0, \frac{\pi}{2}\right)$, among the following conclusions, the correct one is
A. $\sin (\sin \varphi)\cos \varphi>\cos (\cos \varphi)$
C. $\sin (\cos \varphi)>\cos \varphi>\cos (\sin \varphi)$
D. $\sin (\cos \varphi)<\cos \varphi<\cos (\sin \varphi)$
126 D. Use the monotonicity of trigonometric functions to solve.
When $\varphi \in\left(0, \frac{\pi}{2}\right)$, $\sin \varphi\cos \varphi$.
From (1) and (2), we get $\sin (\cos \varphi)<\cos \varphi<\cos (\sin \varphi)$.
Therefore, choose D.