What is the Yahoo complaint feedback loop?

What is the Yahoo complaint feedback loop?
A . It is a tool that enables hard bounces to be automatically recorded in your account as invalid contacts.
B. It is a tool that enables complaints to be automatically recorded in your account as unsubscribes.
C. It is a tool that enables bounces to be automatically recorded in your account as suppressions.
D. It is a tool that enables complaints to be automatically recorded in your account as hard bounces.

Answer: B