According to the textbook, variables change along with the independent variable, making it difficult to pinpoint actual causes. these variables are thus roughly similar to in correlational research.

I believe the answer is: Confounding; Third factors

conclusion that is created by researchers usually based on the relationship between independent and dependent variables. But, confounding and third factors variables both influencing the independent and dependent variables at the same time, which often clouded the true relation between the independent and dependent variables.

answer; ///first they would cross the atlantic ocean, and end up either in europe or africa; good luck