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 $.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:

History plays a lot in people's decision, as many people study scenario's of what happened in the last and use such knowledge to judge for what would be the outcome of those event if they are repeated in the present, although this varies or may turn out a different way sometimes but it is observed that event that occurred in the past and that are replayed in the present usually produce the same result that it produced in the past, most times, this is true for economic decisions.

muslims have taken his goods and products to different parts of asia an indonesia. sometimes just traveled and trade, but in other occasions, stayed in the place and made a living.

trade was the key for muslims economies to prosper. their commerce routes reached far places like malaysia and java in the 11th century.

another important factor for prosperity was that muslim states served as the middle point for european traders.

they used to travel by land but sailing the seas -the indian ocean- really increase the exportation of products.