<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A young infant is brought to an immunologist because of recurrent infections, which have not resolved despite appropriate medical treatment. On reviewing her medical history, the immunologist notes that the child has had frequent disseminated mycobacterial infections. He suspects a possible immunodeficiency. What is the most likely cause of this patients immunodeficiency?? A: B-cell maturation defect, B: ATM gene defect, C: LFA-1 integrin defect, D: Interferon-gamma signaling defect, E: BTK gene defect,  <response>: Based on the information provided in the question stem, the young infant has a history of recurrent infections that have not resolved despite appropriate treatment. She also has a history of frequent disseminated mycobacterial infections. This suggests she likely has an immunodeficiency disorder affecting cell-mediated immunity, which is important for controlling mycobacterial infections. The choices provided include defects affecting B cells B-cell maturation defect, BTK gene defect, T cells LFA-1 integrin defect, and interferon signaling ATM gene defect, interferon-gamma signaling defect. Since mycobacterial infections are controlled by cell-mediated immunity, the defect is most likely in T cells or interferon signaling rather than B cells. Between the T cell and interferon signaling defects, interferon-gamma signaling is critical for immunity against mycobacteria, so an interferon-gamma signaling defect is the most likely cause.D: Interferon-gamma signaling defect 