Answer:
c. Research about aptitude testing
Step-by-step explanation:
Exemption means not to qualify for the requirements to the common rule.
The IRB states that there are certain research studies which includes children as subjects can be exempted under category 2 if the research study is subjected to the Subpart D of the IRB rule. However IRB does not permit any exemption if it includes any identifiable information but is reviewed under the limited IRB review.
Such study which permits exemption under category 2 includes research done on children about aptitude testing.