Implementing an allow list is the best approach because it enables the security team to explicitly permit traffic from known and authorized sources while implicitly denying all other traffic, thus ensuring that only traffic from authorized sources can access the application. In contrast, a blocklist would only prevent access from known unwanted sources, not guarantee that only authorized traffic can access the application. On the other hand, micro-segmentation and network flows are more suited for internal traffic management and would not specifically restrict access to authorized external entities.