Which theorem or postulate justifies this statement? ∠8≅∠10

alternate interior angles theorem
corresponding angles postulate
alternate exterior angles theorem
vertical angles theorem
linear pair postulate

The figure shows parallel line segments G N and F H rising slowly from left to right with segment G N above segment F H. Line segment K L falls steeply from left to right, first intersecting segment G N and then segment F H. Line segment M J rises steeply from left to right, first intersecting both segment F H and segment K L at their point of intersection and then intersecting segment G N. The 4 angles at the intersection of segments G N and K L are numbered from 1 through 4 in a clockwise direction with angle 1 above segment G N and to the left of segment K L. The 4 angles at the intersection of segments G N and J M are numbered from 5 through 8 in a clockwise direction with angle 5 above segment G N and to the left of segment J M. The 6 angles at the intersection of segments F H, K L, and J M are numbered from 9 through 14 in a clockwise direction with angle 9 above segment F H, to the right of segment K L, and to the left of segment J M.