Which statements prove that a quadrilateral is a parallelogram? Select each correct answer.

Quadrilateral DEFG has two sets of consecutive angles that are supplementary.

Quadrilateral DEFG has one diagonal that bisects the other diagonal.

Quadrilateral DEFG has only one set of opposite angles that are congruent.

Quadrilateral DEFG has one set of opposite sides that are both congruent and parallel.

Agroup of student volunteers participates in a study designed to assess several behavioral interventions for improving output in a repetitive task. prior to the beginning of the study, all volunteers unknowingly observed, and their output is measured. at the beginning of the study, prior to any intervention, the volunteers perform the same task under the observation of a study administrator, and their overall output increases. which of the following terms describes this phenomenon? a. simpson's paradox b. hawthorne effect are d. novelty effect d. pygmalion effect e. observer-expectancy effect