<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 30-year-old Caucasian male is brought to the emergency room for recurrent diarrhea. He has had multiple upper respiratory infections since birth and does not take any medications at home. It is determined that Giardia lamblia is responsible for the recurrent diarrhea. The physician performs a serum analysis and finds normal levels of mature B lymphocytes. What other finding on serum analysis predisposes the patient to recurrent diarrheal infections?? A: Deficiency in CD8 T cells, B: Deficiency in neutrophils, C: Deficiency in IgA, D: Deficiency in NK cells, E: Deficiency in IgG,  <response>: This is a clinical vignette about a 30-year-old Caucasian male with recurrent diarrhea caused by Giardia lamblia infection. The question asks about other serum analysis findings that would predispose him to recurrent diarrheal infections. The stem provides several key details:- Recurrent diarrhea due to Giardia lamblia infection- History of multiple upper respiratory infections since birth - Normal levels of mature B lymphocytes on serum analysisGiardia lamblia is a protozoan parasite that causes diarrheal illness. Recurrent infections suggest an immunodeficiency, especially involving mucosal immunity. The normal mature B lymphocyte levels rule out humoral immunodeficiency disorders like X-linked agammaglobulinemia. This points towards a mucosal immunodeficiency disorder. Of the choices given, deficiency in IgA would predispose to recurrent diarrheal infections like Giardiasis. IgA is an immunoglobulin critical for mucosal immunity in the gut. Lack of IgA leads to increased susceptibility to infections by pathogens like Giardia that infect the gastrointestinal tract.C: Deficiency in IgA 