Find the Angle, in Degrees, Between Two Adjacent Sides of the Pyramid

Multiple Choice

Find the angle, in degrees, between two adjacent sides of the pyramid shown below. Round to the nearest tenth of a degree. [Note: The base of the pyramid is not considered a side.]

A) $2.3 ^ { \circ }$
B) $129.8 ^ { \circ }$
C) $90 ^ { \circ }$
D) $45 ^ { \circ }$
E) $39.8 ^ { \circ }$