Which of the following best defines consumer behavior?

Consumer behavior is best defined as the study of individuals and groups in selecting and using products. This definition encompasses not just the purchasing aspect but also the reasons behind the choices consumers make, including psychological, social, and emotional factors that influence decisions. It includes understanding how consumers engage with products throughout the entire lifecycle, from initial consideration to post-purchase evaluation.

The other options focus on specific areas related to marketing but do not capture the holistic view of consumer behavior. For example, analyzing consumer preferences for brands and products highlights a specific aspect of consumer behavior but lacks the broader context of selecting and using products. Similarly, studying pricing's effect on market saturation and investigating advertising effectiveness on sales are both important marketing considerations, yet they do not fully encapsulate the complex set of influences and processes involved in how consumers interact with products and services.