<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 2-year-old boy is brought to the emergency department by his parents after they found him to be lethargic and febrile. His current symptoms started 1 week ago and initially consisted of a sore throat and a runny nose. He subsequently developed a fever and productive cough that has become worse over time. Notably, this patient has previously presented with pneumonia and gastroenteritis 8 times since he was born. On presentation, the patients temperature is 103F 39.4C, blood pressure is 9050 mmHg, pulse is 152min, and respirations are 38min. Based on clinical suspicion, an antibody panel is obtained and the results show low levels of IgG and IgA relative to the level of IgM. The expression of which of the following genes is most likely abnormal in this patient?? A: CD40L, B: STAT3, C: LYST, D: CD18, E: NADPH oxidase,  <response>: This is a clinical vignette about a 2-year-old boy with recurrent infections presenting with fever, lethargy, cough, and abnormal antibody levels showing low IgG and IgA with normal IgM. The question asks which gene is most likely abnormal in this patient. Based on the recurrent infections and abnormal antibody levels, this patient likely has a primary immunodeficiency disorder. The low IgG and IgA with normal IgM points towards a defect in class switch recombination. Therefore, the abnormal gene is most likely involved in regulating class switch recombination.A: CD40L 