Which choices are TCP features?

TCP, or Transmission Control Protocol, is a fundamental protocol used in the Internet Protocol Suite that provides several key features to ensure reliable communication across networks. Understanding these features is essential for managing data transmission effectively.

Flow control is a mechanism that ensures a sender does not overwhelm a receiver with data. By managing the rate of data transmission, TCP can maintain the performance of the communication link and adapt to varying network conditions.

Packet error recovery is another critical function of TCP. It employs acknowledgment (ACK) messages to confirm the receipt of data packets. If packets are lost or corrupted during transmission, TCP can identify the missing data through sequence numbers and retransmit them, ensuring that the data stream remains intact and consistent.

Demultiplexing multiple applications refers to TCP's ability to support multiple connections simultaneously. It does this through the use of port numbers, allowing different applications to send and receive data over the same network connection without interfering with one another. This way, TCP can direct incoming data to the correct application based on the specified port number.

Given these comprehensive features—flow control, packet error recovery, and demultiplexing multiple applications—it is clear that the complete set of important TCP characteristics is covered, making the choice that includes all of these features the correct answer.