After administering a medication to your client, you realize you gave him another client's drug. Your most appropriate action is to:

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

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

Call his physician immediately and make out an incident report.

Check the client's MAR for drug allergies, and if he's not allergic to the drug administered and it is not contraindicated for his condition, do not do anything further about it.