The following results are obtained:

The RV/TLC ratio from these data is consistent with which of the following?

A 6-year-old child has a history of repeated episodes of wheezing and shortness of breath. A pulmonary function technologist has difficulty obtaining repeatable spirometry results. Which of the following tests should be performed next?

Which of the following may cause a reduction in end-tidal CO2?

The following test results are available for a 35-year-old subject who is applying for disability:
These findings are consistent with

While performing a quality control test on an open circuit nitrogen system, the volume of a 3-liter syringe is measured as 3.9 L. Which of the following is the most probable explanation?