Which option in Azure helps you manage network security across multiple Azure resources?

The Network Security Group (NSG) is a fundamental component in Azure that allows you to manage and enforce network security rules across multiple resources, such as virtual machines or subnets. By utilizing NSGs, you can define inbound and outbound security rules that control the flow of network traffic to and from these resources, ensuring that only authorized traffic is allowed. This centralized approach to managing network security is crucial for maintaining a secure infrastructure in Azure.

In contrast, while Azure Firewall offers extensive capabilities for high-level, centralized protection and can manage network security as well, it primarily focuses on filtering and monitoring traffic at the application layer and is designed for larger enterprise needs. Azure VPN Gateway facilitates secure connectivity between on-premises networks and Azure, rather than managing security across Azure resources. The Application Gateway operates at the application layer and serves load balancing functions along with web application firewall capabilities, but it is not primarily designed for overall network security management.

Thus, the Network Security Group stands out as the optimal option for overseeing network security across various Azure resources.