An otherwise healthy 15-month-old girl is brought to the emergency center by her father due to cough,

An otherwise healthy 15-month-old girl is brought to the emergency center by her father due to cough, posttussive emesis, and subjective fever over the past 3 days. He also thinks her abdomen has been hurting her. Diarrhea started yesterday, with “regular” stooling prior to this illness. She has been drinking well and recently had a wet diaper. Physical examination reveals normal vital signs and a temperature of 99 °F (tympanic membrane), congested nares, shoddy neck lymphadenopathy, and a mildly distended and apparently tender abdomen without obvious guarding. Which of the following is the next best step in your evaluation? A Obtain an abdominal CT B Biopsy lymph node C Collect 24-hour urine for catecholamines D Admit to the hospital for exploratory laparotomy E Reassure parent and await spontaneous resolution