Final answer:
The nurse should understand ethical principles and codes, as well as consider the policies and practices of the institution, as the basis for ethical reasoning in making responsible decisions.
Step-by-step explanation:
The basis for ethical reasoning in making responsible ethical decisions in nursing rests on a variety of factors. One of the key foundations is understanding and applying ethical principles and codes, such as autonomy, beneficence, nonmaleficence, and justice. These principles provide a framework for guiding the nurse's behavior and decision-making process. Additionally, the policies and practices of the institution play a role in ethical reasoning, as they provide guidance on how to navigate specific situations within the healthcare setting.