Confounding cannot be removed by?

All of the above REF: Park 20' edition page 68, http://en.wikipedia.org/wiki/Confounding There are various ways to modify a study design to actively exclude or control confounding variables In Case-control studies assign confounders to both groups, cases and controls, equally. In Coho studies matching is often done by only admitting ceain age groups or a ceain sex into the study population, and thus all cohos are comparable in regard to the possible confounding variable Stratification: Controlling for confounding by measuring the known confounders and including them as covariates in multivariate analyses