Which study focuses on the nature, basis, and extent of knowledge?

The study that focuses on the nature, basis, and extent of knowledge is epistemology. This branch of philosophy examines how knowledge is acquired, what constitutes true knowledge, and the limits of what we can know. It explores various questions regarding belief, justification, and the validity of cognitive processes, thus providing a comprehensive framework for understanding knowledge itself.

In contrast, logic pertains to the principles of valid reasoning and argumentation, helping to discern correct from incorrect reasoning. Metaphysics, on the other hand, deals with the fundamental nature of reality, exploring concepts such as existence, objects, and their properties. Ontology is a subset of metaphysics that specifically examines the nature of being and the categories of existence. Each of these areas contributes to philosophical inquiry but targets different aspects of understanding reality and knowledge.