Fill in the Blank with One of the Words or Phrases

Fill in the blank with one of the words or phrases listed below. $$\begin{array} { l c l l l } \text { transversal } & \text { line segment } & \text { obtuse } & \text { straight } & \text { adjacent } \\\text { right } & \text { volume } & \text { area } & \text { legs } & \text { acute } \\\text { right triangle } & \text { perimeter } & \text { hypotenuse } & \text { vertical } & \text { supplementary } \\\text { similar } & \text { congruent } & \text { square root } & \text { ray } & \text { angle } \\\text { line } & \text { complementary } & \text { vertex } & &\end{array}$$
-When two lines intersect, four angles are formed. Two of these angles that are opposite each other are called ______angles.

A) obtuse
B) straight
C) adjacent
D) vertical