Please help! Tiana has a triangular piece of construction paper. She cuts the paper into three pieces. ( the first pic)
Then, she rearranges the three pieces as shown. (second pic)

What do the pieces of Tiana's triangle show?

A
The sum of the interior angles of a triangle is equal to the measure of a straight angle.

B
The sum of two interior angles of a triangle is equal to the measure of a right angle.

C
The sum of the interior angles of a triangle is equal to the sum of the interior angles of a pentagon.

D
The sum of the interior angles of a triangle is equal to the sum of the interior angles of a quadrilateral.