we know that
Alternate interior angles are two interior angles which lie on different parallel lines and on opposite sides of a transversal. Alternate interior angles are congruent
see the attached figure with letters to better understand the problem
in this problem
the parallel lines are the lines a and b
the transversal line is the line c
so
the alternate interior angles are the Angle [tex]3[/tex] and Angle [tex]6[/tex]
m∠3=m∠6
therefore
the answer is the option
Angle [tex]3[/tex] and Angle [tex]6[/tex]
