A flow-volume graph is used to plot the results of which test?

A flow-volume graph is specifically used to represent the results of a forced expiration spirometry test, which measures how air is expelled from the lungs during forced breathing. This type of graph displays the relationship between the airflow (or flow rate) and the volume of air exhaled, providing visual insight into a person's respiratory function and efficiency.

In forced expiration spirometry, the patient takes a deep breath and then exhales forcefully into a spirometer. The resulting data is plotted on a flow-volume graph, showing both the dynamic flow of air and the total volume breathed out. This information is critical in diagnosing and assessing respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and other pulmonary disorders.

The other choices do not relate to the flow-volume graph: visual acuity tests assess eyesight, blood pressure tests measure cardiovascular health, and electrocardiograms evaluate heart rhythms and electrical activity. Thus, the flow-volume graph is uniquely associated with lung function testing through forced expiration spirometry.