What action will keep DoD data the safest?

Leaving the coffee shop is a prudent action that can significantly increase the safety of DoD data. Public spaces like coffee shops are often breeding grounds for cyber threats, where unauthorized individuals can easily observe sensitive information being accessed on devices, particularly if those devices are connected to unsecured Wi-Fi networks. By physically removing oneself from such an environment, the risk of falling prey to shoulder surfing or eavesdropping by malicious actors is greatly diminished.

In contrast, other actions such as changing seats or disabling Wi-Fi may provide only a temporary shield against potential threats. Changing seats might still leave a user vulnerable to prying eyes, while disabling Wi-Fi doesn't fully address the risk of someone accessing your data directly if a device is compromised. Notifying a supervisor, although important in certain contexts, does not provide immediate protection against data breaches or cyber threats that can occur in public settings. Thus, leaving the coffee shop stands out as the most effective measure for safeguarding DoD data in this scenario.