What can you say about the marked angles in these parallelogram?

A Opposite angles of a parallelogram are congruent. ( the same measure)
B Consecutive angles of a parallelogram are supplementary (measure add to 180)
C consecutive angles of a parallelogram are congruent. (The same measure)
D Opposite angles of a parallelogram are supplementary (measure add to 180)


Please need help on this don’t understand this one