A large financial institution recently adopted a Bring Your Own Device $($BYOD$)$ policy. It understands the cost and flexibility advantages of this approach but is concerned about the potential security implications. Specifically, the institution wants to ensure that its sensitive data remains protected even when accessed from or stored on employees' personal devices. What would be the MOST effective strategy to safeguard data in this context?

A$.$ Regularly update the company's firewall and antivirus software

B$.$ Deploy a Mobile Device Management $($MDM$)$ solution

C$.$ Implement mandatory password changes every $30$ days

D$.$ Conduct regular security training for employees