What is the primary purpose of stateful pattern recognition in Cisco IPS networks?

What is the primary purpose of stateful pattern recognition in Cisco IPS networks?

A.
mitigating man-in-the-middle attacks

B.
using multipacket inspection across all protocols to identify vulnerability-based attacks and to
thwart attacks that hide within a data stream

C.
detecting and preventing MAC address spoofing in switched environments

D.
identifying Layer 2 ARP attacks