Which of the Following Describes the Classical Pathway of Complement

Which of the following describes the classical pathway of complement activation?

A) Complement proteins activate when triggered by macrophages or neutrophils.
B) Complement proteins activate when mannose- binding lectin binds to the pathogen.
C) Complement proteins activate by coming into contact with certain blood- clotting proteins.
D) Complement proteins activate when antibodies bind to a pathogen.
E) Complement proteins activate by directly interacting with the pathogen.