Residential HVAC Installation Practice Exam

The correct answer is a round duct system because plenum, extended plenum, reducing plenum, and perimeter loop are all configurations that can be found in round duct systems. Round duct systems are commonly used in residential HVAC installations due to their efficiency and ease of installation.

Rectangular duct systems, which are mentioned in choice C, do not typically have configurations like plenum, extended plenum, reducing plenum, or perimeter loop.

Spiral duct systems, mentioned in choice A, are a type of round duct system but do not specifically refer to the configurations listed in the question.

Oval duct systems, mentioned in choice D, also do not typically have the specific configurations mentioned in the question.