After administering a medication to a client, the nurse realizes that the client was given another client's drug. What must the nurse do next?

Document the error on the client's medical record and notify the supervisor.

Check the client's MAR for drug allergies, and if there is no indicated allergy to the drug administered in error, no further action is necessary.

Call the health care provider immediately and complete an incident report.

Administer the original drug and observe the client frequently for adverse reactions to the first drug.