Answer:
(C)
Explanation:
Let us consider that c is parallel to d and p is the transversal, then using the properties of parallel lines, we have
( By alternate exterior angles)
and
(By corresponding angles)
From the given options,

Thus, the set of equation to prove that lines c and d are parallel lines cut by transversal p is (C) m∠2 = 99° and m∠4 = 99°
Hence, option (C) is correct.