<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 2-day-old newborn male delivered at 38 weeks gestation is evaluated for poor feeding and irritability. His temperature is 35C 95F, pulse is 168min, respirations are 80min, and blood pressure is 6030 mm Hg. Blood culture on sheep agar grows motile, gram-positive bacteria surrounded by a narrow clear zone. Further testing confirms the presence of a pore-forming toxin. Which of the following is the most important factor in successful clearance of the causal pathogen?? A: Secretion of interferon-α from infected cells, B: Formation of the membrane attack complex, C: Interferon-γ-induced macrophage activation, D: Secretion of interleukin 10 by regulatory T cells, E: Secretion of immunoglobulin G from plasma cells,  <response>: This is a medical question asking about the most important factor in clearing an infection in a newborn baby. Based on the details provided, the baby has signs of sepsis including low temperature, rapid pulse and breathing, and low blood pressure. The gram-positive bacteria growing on blood culture with a clear zone and pore-forming toxin indicates the bacteria is likely Staphylococcus aureus. The choices describe different immune responses. Interferon-α and interleukin-10 are more involved in viral infections rather than bacterial. Immunoglobulin G takes time to develop and would not be the most immediate important factor. The membrane attack complex is part of the complement system which is also not the most critical here. Macrophage activation by interferon-γ is the key cell-mediated immune response to clear extracellular bacterial pathogens like S. aureus. Activated macrophages can phagocytose and kill the bacteria.C: Interferon-γ-induced macrophage activation 