Answer:
D.In a parallelogram, opposite angles are congruent.
Step-by-step explanation:
We are given that Helen draws three parallelograms.
We have to find conjecture which is reasonable for Helen to make.
We know that in parallelogram opposite angles are congruent.
Opposite sides of parallelogram are equal and parallel.Consecutive angles are supplementary.
In each figure, opposite angles are congruent.
Therefore, option D is true.
Answer:D.In a parallelogram, opposite angles are congruent.