The triangles are similar because corresponding angles are congruent, however no congruency statement can be made because the side lengths are unknown.
The 4th selection is appropriate.
If you were to take a knife and cut this shape down the middle, starting from the top, what will the cross section look like?
It will look a lot like how the object looks from the side.
The best answer is D, the last image.
Let
3x----> angle exterior 1
4x----> angle exterior 2
5x----> angle exterior 3
we know that
The exterior angles of any polygon add up to 360 degrees
so
3x+4x+5x=360-------> 12x=360----------> x=30°
The largest of exterior angles is equal to the smallest of interior angles
so
the largest of exterior angles is 5x------> 5*30=150°
the smallest of interior angles is 180°-150°=30°
therefore
the answer is
the smallest of interior angle measure 30 degrees