<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 4-year-old boy is brought to the physician in December for episodic shortness of breath and a nonproductive cough for 3 months. These episodes frequently occur before sleeping, and he occasionally wakes up because of difficulty breathing. His mother also reports that he became short of breath while playing with his friends at daycare on several occasions. He is allergic to peanuts. He is at the 55th percentile for height and weight. Vital signs are within normal limits. Examination shows mild scattered wheezing in the thorax. An x-ray of the chest shows no abnormalities. Which of the following is the most likely diagnosis?? A: Cystic fibrosis, B: Asthma, C: Cardiac failure, D: Primary ciliary dyskinesia, E: Tracheomalacia,  <response>: This is a clinical case scenario about a 4-year-old boy with symptoms of shortness of breath, coughing, and wheezing, which occur mostly at nighttime and with physical activity. He has a history of peanut allergy. The description of episodic wheezing and shortness of breath, especially with triggers like exercise, suggests asthma as the most likely diagnosis. Cystic fibrosis would present with more persistent symptoms. Cardiac failure is unlikely in a previously healthy child. Primary ciliary dyskinesia and tracheomalacia may cause wheezing but are less common than asthma. The normal chest x-ray makes structural abnormalities like tracheomalacia less likely.B: Asthma 