Which mode consolidates alarms where the Cisco IPS appliance will generate an alert the first time that a signature fires on an address set and then only send a
summary alert for all address sets over a given time interval?

A.
Fire Once

B.
Fire All

C.
Fire Summarize

D.
Summarize

E.
Global Summarize

Explanation:
http://www.cisco.com/en/US/docs/security/ips/5.1/configuration/guide/idm/dmSgEng.html