A Security Administrator Wants to Implement Two-Factor Authentication for Network

A security administrator wants to implement two-factor authentication for network switches and routers. The solution should integrate with the company's RADIUS server, which is used for authentication to the network infrastructure devices. The security administrator implements the following: An HOTP service is installed on the RADIUS server. The RADIUS server is configured to require the HOTP service for authentication. The configuration is successfully tested using a software supplicant and enforced across all network devices. Network administrators report they are unable to log onto the network devices because they are not being prompted for the second factor. Which of the following should be implemented to BEST resolve the issue?

A) Replace the password requirement with the second factor. Network administrators will enter their username and then enter the token in place of their password in the password field.
B) Configure the RADIUS server to accept the second factor appended to the password. Network administrators will enter a password followed by their token in the password field.
C) Reconfigure network devices to prompt for username, password, and a token. Network administrators will enter their username and password, and then they will enter the token.
D) Install a TOTP service on the RADIUS server in addition to the HOTP service. Use the HOTP on older devices that do not support two-factor authentication. Network administrators will use a web portal to log onto these devices.