Given that e∥f and g is a transversal, we know that m∠4∼m∠5 by the alternate interior angles theorem. We also know that m∠1∼m∠4 and m∠5∼m∠8 by the ________. Therefore, m∠1∼m∠8 by the substitution property.
a. Corresponding angles theorem.
b. Consecutive interior angles theorem.
c. Alternate exterior angles theorem.
d. Angle-side-angle postulate.