The nonequivalent comparison group design can yield several possible outcomes. In one scenario, the experimental group scores higher than the control group at the start of the experiment, and only the experimental group's scores increase from pretesting to posttesting. This could reflect an influence of the independent variable. However, it could also reflect:____________
a) a local instrumentation effect.
b) a attrition effect in the control group.
c) simply that the experimental group was studied for a longer time period than the control group.
d) selection-maturation effect.

Based on the scenario being described within the question it can be said that this could also equally reflect the selection-maturation effect. This term refers to a differential rate of normal growth that occurs between pre-test and pos-tests. Such as is the case in this scenario since the scores have increased drastically between these two stages of the testing period.

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