How does QoS traffic shaping alleviate network congestion?

How does QoS traffic shaping alleviate network congestion?
A . It drops packets when traffic exceeds a certain bitrate.
B . It buffers and queue packets above the committed rate.
C . It fragments large packets and queues them for delivery.
D . It drops packets randomly from lower priority queues.

Answer: B

Explanation:

Reference: https://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos-policing/19645-policevsshape.html