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

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

View Answer

Answer: D