Proofs with transformations

\overset{\leftrightarrow}{K L}

and

\overset{\leftrightarrow}{M N}

are parallel lines.

O

is the midpoint of segment

L M

Which transformation of the plane can we use to prove angles $u$ ‍ and $v$ ‍ are congruent, and why?

(Choice A)
A $180 °$ ‍ rotation about $O$ ‍ maps ray $\vec{L K}$ ‍ onto $\vec{M N}$ ‍ and vice versa, and the same for rays $\vec{L O}$ ‍ and $\vec{M O}$ ‍. This means angle $u$ ‍ will be mapped onto angle $v$ ‍ and vice versa.
(Choice B)
A translation along the directed line segment $M L$ ‍ maps line $\overset{\leftrightarrow}{M N}$ ‍ onto line $\overset{\leftrightarrow}{K L}$ ‍ and angle $v$ ‍ onto angle $u$ ‍.
(Choice C)
A reflection over a line through $O$ ‍ that is parallel to $\overset{\leftrightarrow}{K L}$ ‍ and $\overset{\leftrightarrow}{M N}$ ‍ maps ray $\vec{L K}$ ‍ onto $\vec{M N}$ ‍ and vice versa, and the same for rays $\vec{L O}$ ‍ and $\vec{M O}$ ‍. This means angle $u$ ‍ will be mapped onto angle $v$ ‍ and vice versa.

High school geometry