<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 66-year-old man comes to the physician because of a 3-month history of constipation and streaks of blood in his stool. He has had a 10-kg 22-lb weight loss during this period. Colonoscopy shows an exophytic tumor in the sigmoid colon. A CT scan of the abdomen shows liver metastases and enlarged mesenteric and para-aortic lymph nodes. A diagnosis of stage IV colorectal cancer is made, and palliative chemotherapy is initiated. The chemotherapy regimen includes a monoclonal antibody that inhibits tumor growth by preventing ligand binding to a protein directly responsible for epithelial cell proliferation and organogenesis. Which of the following proteins is most likely inhibited by this drug?? A: ALK, B: EGFR, C: TNF-α, D: VEGF, E: CD52,  <response>: This is a clinical vignette describing a 66-year-old man with a 3-month history of constipation, blood in stool, weight loss, and colonoscopy findings consistent with colorectal cancer that has metastasized to the liver and lymph nodes. He is started on palliative chemotherapy including a monoclonal antibody. The question asks which protein is most likely inhibited by the monoclonal antibody described. Based on the information provided, this antibody inhibits tumor growth by preventing ligand binding to a protein responsible for epithelial cell proliferation and organogenesis. Of the answer choices provided, EGFR epidermal growth factor receptor is the most consistent with the description of the antibodys mechanism of action. EGFR is a receptor tyrosine kinase that promotes epithelial cell proliferation and growth when activated by binding of ligands such as EGF and TGF-alpha. Inhibiting EGFR would prevent these proliferative signals.The other answer choices do not match the described mechanism of action of the antibody:- ALK is not known to be involved in epithelial organogenesis- TNF-alpha is an inflammatory cytokine, not a growth factor receptor - VEGF promotes angiogenesis, not epithelial proliferation- CD52 is expressed on lymphocytes and would not affect epithelial growthB: EGFR 