Q. A 4-month-old baby girl is brought to the pediatrician by her parents due to persistent cough, poor weight gain, and recurrent respiratory infections. Her mother mentions that the baby's skin tastes salty when she kisses her. The baby's vital signs are as follows: temperature 37.2°C (99°F), heart rate 140 beats/min, respiratory rate 45 breaths/min, and blood pressure 80/45 mm Hg. On physical examination, the baby has bilateral crackles, mild wheezing. A sweat chloride test is ordered. Which of the following is the most likely diagnosis?