The Flynn effect is an example that shows a difference in IQ among :

a. ages
b. genders
c. cohorts
d. cultures

Ok, i tried this one, and i thought the answer was "generations"...so i am confused as to what the answer is.

2 answers

Cohorts is similar to generations. The definition of cohorts is "a group of persons sharing a particular statistical or demographic characteristic." For example, a cohort could be all children born in 1980.

Also, you can basically figure out that the answer is cohorts just be eliminating the other answers. The Flynn effect is the continuous rising of IQs over time. So, the answer is definitely not ages or genders. Cultures can't really be right, either. So, it leaves you with cohorts.

Hope this helps. :)
Check this site.

http://en.wikipedia.org/wiki/Flynn_effect

Perhaps #a refers to a progression from one time period to another. I would agree with your generations idea.