Which is true regarding the function of complement components C3a and C5a? a. They decrease blood vessel permeability, isolating the microbe to the site of infection b. C3a and C5a form the alternative membrane attack complex (MAC) c. They are used to increase C3b deposition on the pathogen surface d. C3a and C5a are anaphylatoxins, meaning that they can sometimes cause an uncontrolled inflammatory reaction in tissues throughout the body