What can cause this situation to occur?

During Cisco IPS appliance troubleshooting, you notice that all the signatures are set to Fire All.
What can cause this situation to occur?

A.
A new signature engine update package has been loaded to the Cisco IPS appliance.

B.
A new signature/virus update package has been loaded to the Cisco IPS appliance.

C.
Summarizer has been disabled globally.

D.
All the signatures have been set to the default state.

E.
All the signatures have been retired, and then unretired.

Explanation:
I believe this is the correct explanation

http://www.cisco.com/en/US/products/sw/secursw/ps2113/products_tech_note09186a0080838bc f.shtml