Design a hypothetical experiment to test the importance of direct interaction between T cell receptors and antigens in T cell activation.

• A. Assess T cell proliferation in the presence of various co-stimulatory molecules.
• B. Compare cytokine release in T cells exposed to different pathogens.
• C. Use a mutant T cell line lacking T cell receptors and measure activation levels.
• D. Measure antibody production in T cells with and without antigen exposure.

Answer: (C)