Which of the following provides simple authentication to access network devices while also providing logging...

The correct answer is A. TACACS+. This protocol is commonly used for authentication, authorization, and accounting (AAA) when administrators need to access network infrastructure devices such as routers, switches, and firewalls. The key part of the question is not just authentication, but also logging capabilities. TACACS+ supports accounting functions, which means it can record administrative actions and login events. That makes it especially useful when organizations want traceability for device access and configuration changes.

The other options do not fit as well. SAML is primarily used for federated identity and web-based authentication between identity providers and service providers. SSO is a general authentication convenience feature that allows one login to access multiple systems, but it does not itself provide detailed device-level accounting. MFA strengthens authentication by requiring multiple factors, but it is not the protocol best known for centralized access control and activity logging on network devices.

For Network+ exam purposes, TACACS+ is strongly associated with administrative access to network equipment and with maintaining an audit trail of who accessed devices and what actions were performed. Because the question asks for both simple authentication and logging, TACACS+ is the best match.