What is the benefit of the parallel signature scanning feature in Cisco IOS IPS Software?

A.
Scans multiple patterns within a Signature Micro Engine at any given time

B.
Scans traffic patterns serially and correlates the events in parallel

C.
Dynamically runs detection scanning rules in parallel within a Signature Micro Engine to increase IPS performance

D.
Runs currently configured scanning rules in parallel while updating new signature definition files to reduce the risk of day-zero attacks

Explanation:
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t8/feature/guide/gt_fwids.html
Cisco IOS IPS supports parallel signature scanning. The signatures are scanned in parallel by a Single Micro-Engine (SME). This speeds up the detection and prevention of attacks. SME is one of the two main components of Cisco IOS IPS. The other component is the Signature Definition File (SDF) that contains the signatures. An SME loads the SDF file and scans traffic for signature pattern matching with the signatures in the SDF files.