Alex is writing statements to prove that the sum of the measures of interior angles of triangle PQR is equal to 180°. Line M is parallel to line N. Line N measures 40°, 60°, and 80°. Which is a true statement he could write?

a) Angle PRQ measures 40°.
b) Angle PQR measures 60°.
c) Angle QRP measures 80°.
d) Angle PQM measures 60°.