What are well-known ports used for?

Well-known ports are controlled and assigned by the Internet Assigned Numbers Authority (IANA) for specific services, which is why option B is correct. These ports, ranging from 0 to 1023, are associated with widely used internet protocols and services. For example, port 80 is designated for HTTP traffic, while port 443 is used for HTTPS. By having a standardized set of port numbers assigned for these protocols, it enables consistent communication across networks and systems, ensuring that data is correctly routed to the right application.

The other choices do not accurately reflect the purpose of well-known ports. Some ports are not specifically designated for high-level security protocols; rather, they are allocated based on the functionality of the service they provide. Additionally, well-known ports are not for personal use; they are intended for public protocols and services that everyone can use. Lastly, these ports are not limited to private networks but are essential for internet-wide communication, making them applicable to all networks, both public and private.