Exam CIPT topic 1 question 116 discussion

SCENARIO -
Please use the following to answer the next question:
Chuck, a compliance auditor for a consulting firm focusing on healthcare clients, was required to travel to the client's office to perform an onsite review of the client's operations. He rented a car from Finley Motors upon arrival at the airport as so he could commute to and from the client's office. The car rental agreement was electronically signed by Chuck and included his name, address, driver's license, make/model of the car, billing rate, and additional details describing the rental transaction. On the second night, Chuck was caught by a red light camera not stopping at an intersection on his way to dinner. Chuck returned the car back to the car rental agency at the end week without mentioning the infraction and Finley Motors emailed a copy of the final receipt to the address on file.
Local law enforcement later reviewed the red light camera footage. As Finley Motors is the registered owner of the car, a notice was sent to them indicating the infraction and fine incurred. This notice included the license plate number, occurrence date and time, a photograph of the driver, and a web portal link to a video clip of the violation for further review. Finley Motors, however, was not responsible for the violation as they were not driving the car at the time and transferred the incident to AMP Payment Resources for further review. AMP Payment Resources identified Chuck as the driver based on the rental agreement he signed when picking up the car and then contacted Chuck directly through a written letter regarding the infraction to collect the fine.
After reviewing the incident through the AMP Payment Resources' web portal, Chuck paid the fine using his personal credit card. Two weeks later, Finley Motors sent Chuck an email promotion offering 10% off a future rental.
What is the strongest method for authenticating Chuck's identity prior to allowing access to his violation information through the AMP Payment Resources web portal?