A researcher pretests a group of participants to determine their attitudes toward the use of alternative energy sources to replace crude oil. The researcher then initiates a program to convince them that they should invest in such alternatives. During this time, the price of gasoline rises $0.50 per gallon. At the end of the program, the researcher retests and finds that the participants are much more positive in their attitudes. What threat to internal validity most likely accounts for this change?

history          

Explanation:

In statistics or research methods, there are mainly eight different types of threats associated with internal validity including maturation, instrumentation, selection, testing, history, experimental morality, regression, and interaction of threats.

History: The term "history threat" is one of the different threats to internal validity which is described as an event that generally occurs between posttest and pretest that specific groups experience it differently.

answer; utilitarian;