The AI agrees with the suggested answer of C.
The suggested answer is C: Institute detection and authentication controls for all devices used for network connectivity and data storage.
Reasoning: In a BYOD environment, the risk to the organization's network increases due to the diverse and potentially unmanaged devices accessing it. Implementing detection and authentication controls is essential for several reasons:

Identifying Devices: Detection controls allow the organization to identify the devices attempting to connect to the network. This is the first step in ensuring that only authorized devices gain access.
Authenticating Users and Devices: Authentication controls verify the identity of both the user and the device. This helps to prevent unauthorized access to the network and data.
Enforcing Security Policies: Once a device is authenticated, security policies can be enforced, such as requiring a certain level of encryption or the installation of security software.
Monitoring and Auditing: Detection and authentication controls provide valuable data for monitoring and auditing network activity. This can help to identify and respond to security incidents.

These controls are fundamental to securing the network in a BYOD environment. They help to ensure that only authorized devices and users can access the organization's resources.
Reasons for not choosing other options:

A: Limit the use of the employee devices for personal use to mitigate the risk of exposure to organizational data. While limiting personal use can reduce some risks, it is often difficult to enforce and doesn't address the underlying security issues of potentially compromised devices connecting to the network.
B: Ensure that relevant access to key applications is strictly controlled through an approval and review process. This is a good practice, but it focuses on application access rather than the initial network connection, which is the first point of vulnerability. Even if access to applications is controlled, a compromised device can still pose a threat to the network.
D: Use management software to scan and then prompt patch reminders when devices connect to the network. While important for maintaining device security, this approach is reactive. Detection and authentication controls are proactive measures that prevent unauthorized or non-compliant devices from even connecting to the network in the first place. Relying solely on patch reminders doesn't prevent vulnerable devices from connecting and potentially exploiting vulnerabilities before a patch can be applied.

BYOD Security Best Practices, https://www.fortinet.com/resources/cyberglossary/byod-security
BYOD (Bring Your Own Device): Security Risks and Solutions, https://www.beyondtrust.com/resources/glossary/byod-bring-your-own-device