Use a coordinate proof to prove that mid segment mn of triangle pqr is parallel to pr and half the length of pr. which is the first best step?

a. place the triangle on a coordinate grid such that vertex p is at the origin, and pr lies on x-axis.

b. place the triangle on a coordinate grid such that vertex p is on y-axis and vertex r us on the x-axis

c. place the triangle on a coordinate grid such that vertex q is at the origin

d. place the triangle on a coordinate grid such that qr lies on the x-axis and pq lies in the y-axis