Answer with explanation:
A trapezoid is said to be Isosceles , if one pair of Opposite sides are Parallel and one pair of Opposite sides are congruent to each other.
In the given trapezoid,
AB and CD are pair of opposite legs of trapezoid A B CD, which are Parallel to each Other , and AD and BC are Pair of Legs which must be congruent , so that the trapezoid A B CD becomes Isosceles Trapezoid.
Option C: ⇒AD=BC
