You are creating a policy map for VoIP packets. VoIP packets must receive 30 percent of the bandwidth on the S0/0 interface. Jitter and delay should be minimized.

Which of the following commands should you issue from policy-map class configuration mode? (Select the best answer.)

A. priority 30

B. priority percent 30

C. bandwidth 30
D. bandwidth percent 30

Explanation:

You should issue the priority percent 30 command from policymap class configuration mode to allocate 30 percent of the bandwidth of the S0/0 interface to Voice over IP (VoIP) packets. The priority command creates a strict priority queue where packets are dequeued before packets from other queues are dequeued, thereby minimizing jitter and delay. The syntax of the priority command is priority {bandwidth | percent percentage} [burst], where bandwidth is specified in Kbps and burst is specified in bytes. The presence of the priority command in the policy map indicates that low latency queuing (LLQ) is used.
On voice networks, LLQ can be implemented to help reduce jitter. Additionally, you could configure the voice class to a smaller queue size. Although a smaller queue size could result in dropped packets, voice traffic is more tolerant of dropped packets than of delayed packets. A small amount of packet loss is not noticeable to the human ear. Additionally, some codecs can correct small amounts of packet loss. Therefore, a smaller queue size combined with the use of LLQ could reduce delay and jitter.
You should not issue the priority 30 command from policymap class configuration mode. The priority 30 command ensures that the traffic queue has 30 Kbps of guaranteed bandwidth during periods of congestion, not 30 percent of the bandwidth on the interface.
You should not issue the bandwidth 30 command from policymap class configuration mode. The syntax of the bandwidth command is bandwidth {bandwidth | percent percentage | remaining percent percentage}, where bandwidth is specified in Kbps. Therefore, the bandwidth 30 command ensures that the traffic queue has 30 Kbps of guaranteed bandwidth, not 30 percent of the bandwidth on the interface. If a policy map contains only bandwidth commands but no priority commands, only classbased weighted fair queuing (CBWFQ) is used.
You should not issue the bandwidth percent 30 command from policymap class configuration mode. Although the bandwidth percent 30 command ensures that packets receive 30 percent of the bandwidth on the interface, it does not minimize jitter and delay.

Reference:
https://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos-packet-marking/10100-priorityvsbw.html