What does a packet sniffer do?

What does a packet sniffer do?

A.
It performs port scans and footprinting.

B.
It identifies cabling faults.

C.
It detects hanging modems not protected by the firewall.

D.
It captures traffic for data analysis.

Explanation:
A sniffer is a tool that captures frames from a network for viewing
purposes. Most sniffers put the systems NIC into promiscuous mode so that all
traffic can be monitored.