In a case-control study, cases and controls are often matched on variables such as age and sex. This is to make cases and controls:

In a case-control study, matching cases and controls on specific variables like age and sex aims to create a more comparable group. This approach allows researchers to minimize confounding effects that those demographic variables might introduce into the study. By ensuring that the groups are similar in these aspects, the focus remains on the disease or health characteristic being evaluated.

The correct answer highlights that the primary goal of matching is to make cases and controls similar regarding factors, except for the disease or health characteristic that is the central focus of the study. This helps isolate the relationship between the disease and any other variables under consideration while ensuring that any observed differences in outcomes can be attributed to the disease rather than other confounding factors.