What is the FirePOWER impact flag used for?

A.
A value that indicates the potential severity of an attack.

B.
A value that the administrator assigns to each signature.

C.
A value that sets the priority of a signature.

D.
A value that measures the application awareness.

Explanation:
BD
Impact Flag: Choose the impact level assigned to the intrusion event.
Because no operating system information is available for hosts added to the network map from NetFlow data,
the system cannot assign Vulnerable (impact level 1: red) impact levels for intrusion events involving those
hosts. In such cases, use the host input feature to manually set the operating system identity for the hosts.
Source: http://www.cisco.com/c/en/us/td/docs/security/firepower/60/configuration/guide/fpmc-config-guide-v60/
Correlation_Policies.html
Impact
The impact level in this field indicates the correlation between intrusion data, network discovery data, and
vulnerability information.
Impact Flag
See Impact.
Source: http://www.cisco.com/c/en/us/td/docs/security/firesight/541/firepower-module-user-guide/asa-firepowermodule-user-guide-v541/ViewingEvents.html