The following feature is common to both cytotoxic T cells and NK cells:
Synthesize antibody
Require antibodies to be present for action
Effective against virus infected cells
Recognize antigen in association with HLA class II markers
Answer is B (Effective against virus infected cells) : Common to both cytotoxic T cells and NK cells is affectivity against virus infected cells. Natural Killer cells: Are first line of defense against virus laden cells and neoplastic cells. Cytotoxicity is not MHC restricted. Cvtotoxic T cells: They are antigen specific T cells whose function is to produce antigen specific lysis of target cells by direct cell-tocell contact. Are usually CD + class I MHC restricted T cells. Are impoant in defense against viral infections of tissues. Thus the feature common to both cytotoxic T cells and NK cells is affectivity against virus infected cells.