What is the difference between the OSI model's 'Connection-Oriented' service and 'Connectionless' service at the Transport layer, and which Transport layer protocol exemplifies each?

• A.Connection-Oriented uses dedicated circuits; Connectionless uses packet switching
• B.Connection-Oriented service (TCP): a logical connection is established before data transfer (3-way handshake), data is sequenced and guaranteed to be delivered in order and reliably (ACKs, retransmission), and the connection is formally terminated (4-way FIN). Connectionless service (UDP): no connection establishment; each datagram is independent; no delivery guarantee, no ordering, no flow control; lower overhead and latency
• C.Connection-Oriented uses IPv6; Connectionless uses IPv4
• D.