The five sides of a regular pentagon are all equal in length. Also, all interior angles of a regular pentagon have the same measure. In the diagram, $P Q R S T$ is a regular pentagon and $\triangle P U T$ is equilateral. The measure of obtuse $\angle Q U S$ is
(A) $172^{\circ}$
(B) $168^{\circ}$
(C) $170^{\circ}$
(D) $176^{\circ}$
(E) $174^{\circ}$

![](https://cdn.mathpix.com/cropped/2024_04_20_ac36362783317e0251fdg-028.jpg?height=382&width=396&top_left_y=999&top_left_x=1344)