Reading smoke is primarily about comparing smoke attributes from various ____ and cracks.

Reading smoke is primarily about comparing smoke attributes from various openings and cracks. In firefighting, openings refer to any gaps or penetrations in a structure where smoke may escape or be drawn in. By observing these openings, firefighters can gain insights into the fire's behavior, indicating its location, intensity, and potential growth.

For example, the color, volume, and velocity of the smoke emanating from these openings can reveal vital information about the fire's phase (whether it is smoldering or in a more active burning stage), the materials that are burning, and how the fire is interacting with the environment. This understanding allows firefighters to make informed decisions about tactics, such as whether to apply water or ventilation strategies.

In contrast, while floors, holes, and ventilation are related concepts, they do not encapsulate the broader range of factors involved in reading smoke. Floors are specific areas within a structure, and discussing holes might focus narrowly on structural integrity rather than the overall context of smoke behavior. Ventilation refers to the management of airflow but does not encompass the act of comparing smoke attributes from various points. Thus, openings encompass all potential areas smoke could emanate from, making it the correct focus for this aspect of firefighting tactics.