What type of research design aims to answer why people behave as they do?

The correct choice, basic research, is designed to increase our understanding of fundamental psychological processes and behavior. It seeks to uncover the underlying reasons behind why individuals act in certain ways, focusing on expanding knowledge within the field rather than solving practical problems. This type of research is driven by curiosity and the desire to explore theoretical concepts, often leading to insights that can later be applied in real-world situations.

In contrast, applied research is focused on solving specific, practical problems and may not delve deeply into the underlying psychological processes. Cross-cultural research examines how different cultures influence behaviors but does not primarily seek to explain the reasons behind those behaviors. Observational research involves systematically watching subjects to gather data on their behaviors but may lack the depth needed to explore the "why" aspect of those behaviors.