Which of the following are types of flow control? (Choose three.)

A.
buffering

B.
cut-through

C.
windowing

D.
congestion avoidance

E.
load balancing

Explanation:
http://www.info-it.net/cisco/ccna/exam-tips/flow-control.php
During Transferof data, a high speed computer is generating data traffic a lot faster than the
network device can handle in transferring to destination, so single gateway or destination
device cannot handle much amount of traffic that is called “Congestion”.
Buffering
The Technie is used to control the data transfer when we have congestion, when a network
device receive a data it stores in memory section and then transfer to next destination this
process called “Buffering”.
Windowing Whereas Windowing is used for flow control by the Transportlayer.
Say the sender device is sending segments and the receiver device can accommodate only a
fixed number of segments before it can accept more, the two devices negotiate the window
size during the connection setup.
This is done so that the sending device doesn’t overflow the receiving device’s buffer.
Also the receiving device can send a single acknowledgement for the segments it has received
instead of sending an acknowledgement after every segment received.
Also, this window size is dynamic meaning, the devices can negotiate and change the window
size in the middle of a session. So if initially the window size is three and the receiving device
thinks that it can accept more number of segments in its buffer it can negotiate with the
sending device and it increase it to say 5 for example.
Windowing is used only by TCP since UDP doesn’t use or allow flow control.