A researcher predicted that the presence of other people (the independent variable) leads to a decrease in math performance (the dependent variable). To test this prediction, the researcher had participants first complete a set of math problems while alone and then, the same participants completed a set of math problems with other people present. After each participant was tested in both conditions, the researcher compared the results. In this study, the researcher used a

participatory design

Step-by-step explanation:

Participatory Design (PD) is defined as an approach that is used for assessment as well as design and development of the technological and the organizational systems.

This method is used to a control and the experimental groups that is as similar as possible. Therefore the participants served their own control group. And so rather than replying the random assignment to produce an equal groups, the researchers have the same group of the participants that experience various conditions in the study.

the answer is b.

step-by-step explanation:

identity property is where 0+whatever number=whatever number. basically 0+ a number.