Final answer:
Verifying the medication administration record (MAR) is the correct documentation that fulfills the 6th 'right' for administering digoxin.
Step-by-step explanation:
The documentation that most correctly fulfills the 6th 'right' for a nurse who just administered a dose of digoxin is option c) Verifying the medication administration record (MAR). This step ensures that the correct medication was given at the correct dose, route, and time. It also helps prevent medication errors and provides a record of the administered medication for future reference.