Which of the following is an example of basic research?

Basic research is primarily focused on increasing our understanding of fundamental principles and theories, often without an immediate application in mind. It seeks to expand knowledge within a specific field, usually through the exploration of concepts and relationships.

The study regarding whether children of divorced parents are more likely to be divorced is an example of basic research as it investigates the underlying relationship between parental divorce and the potential outcomes in children's future marital status. This type of inquiry contributes to our understanding of familial and social dynamics, but it does not directly aim to solve a specific problem or develop a product.

In contrast, the other options represent applied research or practical studies. For instance, a study on the effects of caffeine on alertness seeks to understand how caffeine impacts performance, but it may also aim to provide insights applicable to various fields such as psychology or health. A clinical trial for a new medication is centered around testing its effectiveness and safety for practical medical use. Lastly, market research studies aim to gather data to inform business decisions and strategies, making them primarily practical in nature as well.