The correct answer is TCP establishes a connection and provides reliable delivery while UDP operates without a connection and does not guarantee delivery.

This is correct because TCP performs a connection setup with a three way handshake and it uses sequence numbers acknowledgements and retransmissions to provide reliable and ordered delivery. UDP is connectionless and it sends datagrams without built in acknowledgements or retransmission so packet loss or reordering can occur and delivery is not guaranteed.

Cloud Pub/Sub is incorrect because it names a managed messaging service rather than describing the characteristics of the two transport protocols. It does not address connection setup or delivery guarantees for TCP and UDP.

UDP is intended for short connectionless packets and it does not implement error correction is incorrect because the phrasing is incomplete and slightly misleading. It is true that UDP is connectionless and commonly used for small or low latency messages but UDP still includes a checksum for basic integrity checking and it does not perform retransmission based error correction. The statement does not contrast this behavior with TCP which provides reliable delivery.

TCP never reorders segments and UDP always preserves message order is incorrect because it states absolutes that are not true. Networks can deliver packets out of order and TCP uses sequencing and reassembly to present ordered data to the application. UDP does not guarantee ordering and can deliver datagrams out of order. Saying never or always makes the option wrong.

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