Aesthetics is the study of which of the following?

Aesthetics is fundamentally concerned with the study and appreciation of art and beauty, including the principles that define artistic expression. This branch of philosophy explores what constitutes beauty, how it is perceived, and how it can be represented through various forms of art. It examines not only the creation of art itself but also the inherent values and standards that guide artistic endeavors and influence our reactions to different pieces.

The focus on art and beauty in aesthetics allows individuals to engage deeply with questions such as what makes something beautiful, how emotions are evoked through artistic works, and the societal and cultural impact of aesthetics. This domain thus serves as a bridge connecting artistic practice with philosophical inquiry, allowing for a richer understanding of both fields.

In contrast, the other options cover markedly different areas of study. Ethical theories pertain to morality and principles of right and wrong. Mathematical reasoning deals with the logic and principles involved in mathematics. The nature of existence engages with metaphysics, exploring questions about reality and being. Each of these subjects is distinct and does not encompass the thematic explorations associated with aesthetics.