Question

to perform a smoke test,
room air is pulled through a filter drier.
flue gas is pulled through a filter paper.
room air is pulled through a filter paper.
flue gas is pulled through a filter drier.

Explanation:

A smoke test (in the context of, e.g., combustion or HVAC) typically involves analyzing flue gas. Filter paper is used to capture particulates in flue gas for such tests, while a filter drier is for moisture/impurity removal in refrigeration systems. Room air is not the focus here, and flue gas is analyzed via filter paper for smoke (particulate) detection. So the correct option is the one with flue gas and filter paper.

Answer:

B. flue gas is pulled through a filter paper.