Final answer:
To prove a quadrilateral is a parallelogram, the diagonals must bisect each other, or the opposite angles must be congruent. Only options A, B, E, and F describe these properties correctly.
Step-by-step explanation:
To determine if a quadrilateral is a parallelogram, one must analyze its properties and apply certain theorems and postulates. There are a few key characteristics that prove a quadrilateral is a parallelogram:
- If a quadrilateral's opposite sides are congruent, it's a parallelogram. However, having only one set of opposite sides congruent is not enough to prove it's a parallelogram, which eliminates options C and D.
- If the diagonals of a quadrilateral bisect each other, this is a strong indicator that the shape is a parallelogram, which makes options A and B correct.
- Having opposite angles that are congruent also proves that a quadrilateral is a parallelogram, which confirms options E and F as correct.
- A quadrilateral where only one set of consecutive angles is supplementary does not necessarily make it a parallelogram, ruling out option G.
Therefore, the correct statements proving that a quadrilateral is a parallelogram are that it has diagonals that bisect each other (A and B) and opposite angles that are congruent (E and F).