What does an internet gateway in a VPC do?

An internet gateway in a Virtual Private Cloud (VPC) primarily functions as a target for internet-routable traffic, which facilitates communication between resources within the VPC and the internet. By attaching an internet gateway to a VPC, you enable instances within that VPC to access the internet and for external users to reach those instances if they have public IP addresses.

When an instance needs to communicate with the internet, the internet gateway will route the outbound traffic from that instance to the public internet. Similarly, it can handle incoming traffic from the internet to the instances, allowing for proper routing and addressing. This is essential for applications that need to be publicly accessible or that rely on internet-based services.

The other options refer to functionalities that are not associated with an internet gateway. Load balancing pertains to evenly distributing network or application traffic across multiple servers, while connecting multiple VPCs securely generally involves using VPC peering or AWS Transit Gateway, rather than an internet gateway. Data encryption in transit typically falls under different services and techniques, such as using SSL/TLS protocols. Thus, option B accurately describes the role of an internet gateway in a VPC.