Cytotoxic t cells can attack target cells with which of these chemical weapons?
a) secrete strong acid b) secrete organic solvent c) secrete free radicals d) secrete a cytokine that triggers apoptosis e) secrete mutant proteins

D) secrete a cytokine that triggers apoptosis

Explanation:

Cytotoxic T cells also known as killer cells are lymphocytes that can kill  foreign cells (also cancer cells, damaged and infected cells). They express specific type of receptors called T-cell receptors (TCRs) which recognize antigen of foreign cells. Cytotoxic T cells release cytotoxins such as perforin and granzymes and their role is to trigger the signal cascade in the target cell that will lead to apopotsis.