A nurse failed to administer a medication to a patient according to accepted standards. Consequently, the patient suffered adverse effects. Failure to provide patient care and to follow appropriate standards is called:

Breach of duty refers to the failure to provide the standard of care that a reasonably prudent person would have provided in a similar situation. In this case, the nurse failed to administer medication according to accepted standards, which is a breach of duty. This failure to provide proper patient care led to the patient suffering adverse effects.

Option A, breach of contract, involves the failure to fulfill the terms of a contract. Option B, battery, refers to the intentional harmful or offensive touching of a person without their consent. Option C, tort, is a legal term that encompasses various wrongful acts that result in harm to an individual. However, in this situation, the most appropriate term to describe the nurse's action is breach of duty as they did not meet the standard of care expected in their role.