At the patient of 2 years with recurrent bronchopulmonary disease, malnutrition, diagnosed with cystic fibrosis. Which study should confirm the clinical diagnosis?

Answer options

1. The level of calcium in the blood
2. The presence of protein in the urine
3. The content of the 2-fraction of gamma globulins
4. The level of alkaline phosphatosis in serum
5. The amount of chloride in the sweat