How do TCP and UDP differ in the way they provide reliability for delivery of...

TCP provides reliability mechanisms that UDP does not provide. It uses sequencing, acknowledgments, retransmission, and flow control to deliver a byte stream reliably between endpoints. Flow control matters because a sender must not overwhelm a receiver faster than the receiver can process data; TCP windowing handles that. UDP is connectionless and sends datagrams without establishing a session, tracking sequence numbers, or retransmitting missing data at the transport layer. That does not make UDP useless; it makes UDP lightweight and appropriate for traffic such as DNS queries, DHCP, voice, and video where speed or application-level recovery is more important than transport-layer recovery. Cisco CCNA 200-301 v1.1 Network Fundamentals expects this TCP-versus-UDP distinction. Option C is the best available answer because it correctly states that TCP provides flow control and UDP sends without the same sequencing checks. The other choices reverse the protocols or incorrectly claim UDP provides reliable transfer.