Step 1: Review the core features of TCP.
TCP, or Transmission Control Protocol, is a transport layer protocol that provides reliable and connection-oriented communication.
It allows data to flow in both directions at the same time and follows specific procedures to start and end a connection.
Step 2: Evaluate statement (a).
TCP allows simultaneous sending and receiving of data between the two endpoints.
This means TCP operates in full-duplex mode, not half-duplex.
Therefore, option (a) is incorrect.
Step 3: Evaluate statement (b).
Before data transfer begins, TCP establishes a connection using the three-way handshake process:
\[ \text{SYN} \rightarrow \text{SYN+ACK} \rightarrow \text{ACK} \]
This exchange synchronizes sequence numbers and confirms that both sides are ready to communicate reliably.
Hence, option (b) is correct.
Step 4: Evaluate statement (c).
TCP connection termination is performed through a four-segment handshake, where each side closes its data stream independently.
Connection closing is separate from data transmission initiation and does not occur simultaneously in the manner described.
Thus, option (c) is incorrect.
Step 5: Evaluate statement (d).
Either endpoint in a TCP connection—client or server—can initiate the termination process.
There is no rule requiring only the client to close the connection.
Therefore, option (d) is also incorrect.
Step 6: Final conclusion.
The correct statement about TCP connections is:
\[ \boxed{\text{The client and server use a three-way handshaking mechanism}} \]