<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 6-month-old infant is brought to the physicians office by his parents due to a fever, cough, and shortness of breath. The cough is dry and has been progressively worsening for the past 48 hours along with the shortness of breath. His fever never exceeded 37.8C 100.0F at home. The parents say that he has also had abundant nasal drainage and loss of appetite. He is irritable and vomited twice during this period. He has no relevant medical or family history.His vitals are the following:Pulse rate 165minRespiratory rate 77minTemperature 38.0C 100.4FOn physical examination, there is nasal congestion with thick secretions, accompanied by nasal flaring. On chest examination, intercostal retractions are seen and diffuse wheezing on both sides are heard on auscultation. What is the most likely cause?? A: Asthma, B: Sinusitis, C: Rhinopharyngitis, D: Bronchiolitis, E: Laryngotracheitis,  <response>: This is a clinical case of a 6-month-old infant with fever, cough, shortness of breath, nasal congestion, vomiting, and wheezing. The key findings are the young age of the patient, fever, respiratory distress with wheezing, and lack of any notable medical history. Bronchiolitis is the most likely diagnosis in this case. Bronchiolitis typically affects infants under 2 years old and presents with cough, wheezing, respiratory distress, and low grade fever. The wheezing and respiratory distress point towards a lower respiratory tract infection like bronchiolitis rather than an upper respiratory infection. Asthma is unlikely in an infant this young with no prior history. Rhinopharyngitis and sinusitis would not explain the wheezing. Laryngotracheitis could cause wheezing but is less common than bronchiolitis in this age group.D: Bronchiolitis 