Which of the following best denotes classical complement pathway activation in immunoinflammatory condition -

Ans. is 'a' i.e., C2, C4,C3 decreasedThere are four pathways of complement system :The classical activation pathway activated by antigen / antibody immune complexes.The mannose - binding lectin activation pathway activated by microbes with mannose terminal groups.The alternative activation pathway activated by microbes or tumor cells.The terminal pathway that is common to first three pathways and leads to the membrane attack complex that lyses cells.RememberThe central process in the complement cascade is the activation of C3, which is the major component of complement.