Final answer:
Ethics is the branch of philosophy focusing on right and wrong behavior, with 'c. doing what is right' is the correct phrase to complete the sentence. It encompasses metaethics, normative ethics, and applied ethics, each of which explores different aspects of ethical principles and moral conduct.
Step-by-step explanation:
Regarding the question of what ethics is as a way of behaving, the correct completion for the sentence would be 'c. doing what is right.' Ethics refers to the philosophy concerning principles that define right and wrong behavior. The study of ethics is broken down into three main areas: metaethics, which discusses ethical theories and language; normative ethics, which deals with duty or rules to determine the rightness of actions; and applied ethics, which involves the moral deliberation and application of ethical principles to specific situations. It is fundamental to our social structure as it determines how we are to behave toward one another, with different principles producing different moral rules and practices.