B/C (aerobic exercise strengthens heart & lungs)
Answer:
A longitudinal study
Explanation:
A longitudinal study can be used to discover relationships between variables that are not related to various background variables. This observational research technique involves studying the same group of individuals over an extended period.
He has researched the problem. Good luck!
Adverts influence underage drinking by an overexposure to alcohol ads and showing scenarios in which there is adult approval.
