Which of the following is an example of a confined space?

A confined space is typically defined as a space that has limited means of entry or exit and is not designed for continuous occupancy. In this context, HVAC duct plenums are indeed an example of a confined space because they are enclosed areas that service the heating, ventilation, and air conditioning system. These spaces often have restricted access, which can make work within them hazardous if proper safety measures are not followed.

The nature of duct plenums means that they can also pose risks related to air quality and accessibility, which emphasizes the significance of understanding confined spaces in a commercial drying context. The other options, while they might represent varying levels of enclosure or usability, do not fit the definition of confined spaces in the same way. An office cubicle is designed for work and has clear entry and exit points, an open parking lot is accessible and unobstructed, and a reception area is similarly open and designed for public access.