1. The base edge length of a regular quadrilateral pyramid is 2017, and the side edge length is 2000. Then, the absolute value of the difference between the angle formed by the side edge and the base and the angle on the front face is the smallest for which of the following angles.
A. $30^{\circ}$
B. $40^{\circ}$
C. $50^{\circ}$
D. $60^{\circ}$
Given that the angle between the lateral edge and the base is $\theta$, then $\cos \theta=\frac{2017}{2000} \cdot \frac{\sqrt{2}}{2}>\frac{\sqrt{2}}{2} \Rightarrow \theta<45^{\circ}$, so the answer is $B$.