To determine the cause-and-effect relationships between two variables, a researcher would conduct an experiment. administer a questionnaire. collect archival data. administer an inventory.

Would conduct an experiment.

Explanation:

To determine the cause-and-effect relationships between two variables, a researcher would  conduct an experiment. To prove that a change in the independent variable causes an effect on the dependent variable it is necessary to conduct an experiment. An experiment is a carefully designed procedure in which the independent variable is manipulated by the researcher to observe the effects on the dependent variable.

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