What is the difference between deep packet inspection and stateful inspection?

A.	Deep packet inspection is more secure than stateful inspection on Layer 4
B.	Stateful inspection verifies contents at Layer 4 and deep packet inspection verifies connection at Layer 7
C.	Stateful inspection is more secure than deep packet inspection on Layer 7
D.	Deep packet inspection allows visibility on Layer 7 and stateful inspection allows visibility on Layer 4