What is the unit of data working in the Data Link layer? a) Bit b) Frame c) Segment d) Packet 2. What is the unit of data working in the Transport layer? a) Bit b) Frame c) Segment d) Packet 3. Flow control is used to prevent network congestion. Which one of the following methods is not related to flow control? a) Windowing b) Buffering c) Source-quenching d) Encapsulating