Nimby did an evaluation research study of the impact of after-school programs within schools on the ...

Nimby did an evaluation research study of the impact of after-school programs within schools on the delinquency rates of pre-teens. He was careful to identify what he meant by after-school programs. As part of his study, he examined the changes in availability of after-school programs outside of schools as well as changes in enforcement of delinquency laws. His careful attention to identifying what he meant by after-school programs reflects
 
  a. cost-benefit analysis.
  b. time-series analysis.
  c. specifying the intervention.
  d. specifying the population.
  e. verifying validity