Final answer:
Ethics is defined by option C as a set of principles or standards that distinguish right from wrong. It involves systematizing and recommending concepts of right and wrong behavior within the field of philosophy and is categorized into metaethics, normative ethics, and applied ethics.
Step-by-step explanation:
The term "ethics" best defines a set of principles or standards that differentiate right from wrong, making option C the correct response. Ethics is a field within philosophy that deals with questions of morality, such as the foundation of ethical principles, the criteria for moral conduct, and the analysis of what actions and behaviors are considered morally permissible or impermissible. It is structured into three primary areas: metaethics, which concerns itself with the underlying nature of ethical theories and moral value; normative ethics, which seeks to establish standards that guide morally correct behavior; and applied ethics, which applies these ethical principles to real-world issues and situations to assess the correctness of specific actions.