a. Converse of the alternate interior angles theorem b.Converse of the corresponding angles theorem c. Converse of the same-side consecutive angles theorem d.transitive property

ANSWER
c. Converse of the same-side consecutive angles theorem.
EXPLANATION
In statement 6 it is said that angles 6 and 13 are supplementary and if we consider t1 and t2 as parallel lines, then l2 is the transversal, which makes angles 6 and 13 same-side consecutive angles.