A network administrator needs to limit devices that can connect to a small wireless network.

The correct answer is B. MAC filtering. MAC filtering is a straightforward method of restricting network access by allowing only specific device MAC (Media Access Control) addresses to connect to a wireless network. In a small, stable environment with fewer than ten devices and no expected changes, this approach is simple to implement and manage.

Each network interface card (NIC) has a unique MAC address, and wireless access points can be configured with a whitelist of approved addresses. Devices not on the list are denied access, effectively limiting connectivity to only authorized laptops. This aligns with CompTIA Network+ guidance for basic access control mechanisms in small or low-complexity networks.

Other options are less suitable in this scenario. ACLs (Access Control Lists) are typically used on routers and switches to control traffic flow based on IP addresses or protocols, not specifically device access to a wireless network. NAC (Network Access Control) provides more advanced authentication and posture assessment but is more complex and unnecessary for a small, static environment. Trusted zones refer to network segmentation concepts rather than device-level access control.

Thus, MAC filtering provides the simplest and most appropriate solution.