Which of the following application-layer protocols are based on TCP?

B (Correct) - HTTP: Uses TCP port 80 for web traffic.

C (Correct) - FTP: Uses TCP ports 20/21 for file transfer.

A (Incorrect) - TFTP: Uses UDP port 69, not TCP.

D (Incorrect) - Ping: Uses ICMP, which is neither TCP nor UDP.

Thus, the correct answers are B and C.