Step-by-step explanation:
The question the nurse should ask to determine the client's identity is:
b. What is your full name?
Asking for the client's full name is a common and reliable method to confirm their identity prior to medication administration. It helps ensure that the medication is being administered to the correct person.
The other options mentioned—home phone number, date of birth, hospital or medical record number, and full address—may also be useful for identifying the client, but they are not as reliable or commonly used as asking for the full name.