How Is Significant Clinical Airflow Limitation Determined from Pre- and Postbronchodilator

How is significant clinical airflow limitation determined from pre- and postbronchodilator spirometry?

A) When the patient's FEF 25% to 27% increases by 12% and 200 mL/second
B) When the patient's FEV₁ increases by 12%
C) When the FVC increases by 20% and 200 mL
D) When the FEV₁/FVC ratio increases by 25%