In quadrilateral ABDC, AB ∥ CD. Which additional piece of information is needed to determine that ABDC is a parallelogram? AB ≅

For a quadrilateral to qualify as a parallelogram

i) both pairs of opposing sides must be equal

ii) Both pairs of opposing sides should be parallel

iii) Opposite angle pairs need to match

iv) Diagonals must bisect one another.

v) One pair of opposite sides should be both parallel and equal

In our case, it is given that AB || CD

Thus, we require either AD || BC

or we need that AB = CD

It has been specified that AB = CD as an option.

Therefore, the first option, A) stating AB ≅CD, is necessary to establish that ABCD is a parallelogram.

Response: A

Detailed explanation: