The correct answer is 'Passive Scan'. Passive scanning in ZAP processes the requests and responses that your browser makes to a web application without sending any new requests by itself, with minimal impact on the performance of the application. It is safer to use in a production environment compared to an Active Scan, which can potentially be more invasive as it sends new requests that can affect a live system. The AJAX Spider option is incorrect because while it does provide more insight into AJAX-heavy applications, it actively interacts with them, which may not be desired in a production environment. Lastly, the Forced Browse option is an attack mode in ZAP that actively searches for hidden resources, which can potentially lead to performance degradation or unmasking of unintended content.