The cross-sectional method is subject to the generational effects of having been born at a particular point in history, which is called the a. generational correlation b. historical bias c. age-related differences d. cohort effect

The answer is D. Cohort effect.

Explanation:

A cohort is a group of people that share a characteristic, in social research, such characteristic tends to be the birth year or generational designation; in these cases, cohorts might be strongly influenced by the historical and cultural environment of their generation, and this might have an effect on the results of the research project. Cross-sectional method is subject to these effects because they only apply the research techniques in one specific point in time.

c it has to be i googled it