<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 55-year-old Caucasian male presents for a routine colonoscopy. A polyp is found in the patients transverse colon and is found to be cancerous on histological evaluation. Upon examination, it is found that these cancerous cells have decreased MHC class I expression on their surface. Which immune system cell is most capable of killing these tumor cells?? A: Natural killer cells, B: B-cells, C: Macrophages, D: Eosinophils, E: Cytotoxic T-cells,  <response>: This is a question about immunology and tumor cells. The key information in the question stem is that the cancer cells have decreased MHC class I expression on their surface. MHC class I molecules present antigens to cytotoxic T cells. Since the tumor cells have decreased MHC class I, they will not be well recognized by cytotoxic T cells. The answer choices list different immune cells. Natural killer NK cells are able to recognize and kill tumor cells independent of MHC class I expression. The other cells listed either rely on MHC class I for activation cytotoxic T cells or have other primary functions not related to killing tumor cells B cells, macrophages, eosinophils.A: Natural killer cells 