which can be easily denied with a stateful packet filter?

Of the following packet types, which can be easily denied with a stateful packet filter?

A.
ICMP

B.
TCP

C.
UDP

D.
IP

Explanation:
With ICMP, IP and UDP, each packet is handled individually, with no
reference to the contents of the previous one. With no sessions, these protocols
usually cannot be filtered on the state of the session. Some newer firewalls,
however, simulate the concept of state for these protocols, and filter out
unexpected packets based upon normal usage. Although these are commonly treated like
normal stateful filters, they are more complex to program, and hence more prone to
errors.