What type of access control list (ACL) allows HTTP access to a server at 172.17.80.1 while denying Telnet from the 192.168.10.0/24 network?

B is the correct choice because the requirement is to allow HTTP access to the server at 172.17.80.1, which operates on TCP port 80. The statement "permit tcp 192.168.10.0 0.0.0.255 host 172.17.80.1 eq 80" effectively grants permission for TCP traffic originating from the 192.168.10.0/24 network to reach the specified server on the HTTP port.

Selecting this choice simultaneously supports the objective of letting the specified network access the server while not addressing Telnet, which operates on port 23. Importantly, this does not imply that Telnet access is permitted; rather, it simply does not include any instruction that would allow Telnet from the 192.168.10.0/24 network, thus achieving the goal of denying it by omission.

To further comprehend the context, access control lists typically operate on a "first-match" basis. If a packet does not match any permit statements, it is implicitly denied. Therefore, by listing the permission for HTTP access without specifying Telnet access, the ACL structure enforces the denial of Telnet effectively.