Sub tubes are primarily composed of what materials?

The correct choice indicates that sub tubes are primarily composed of saliva, fecal pellets, and chewed wood. This composition reflects the biological processes of certain organisms, particularly those like termites, which create sub tubes as part of their nesting behavior.

In these tubes, saliva acts as a binding agent, helping to hold the components together while also providing moisture necessary for the survival of the colony. Fecal pellets contribute additional organic material that promotes structural integrity, while chewed wood serves as a primary food source. The combination of these materials creates a suitable environment for the colony and aids in their construction methods.

The other options present materials that do not accurately reflect the composition of sub tubes. Wood and sand, dirt and saliva, and wood and bark do not account for the role of fecal matter and saliva in the biological context, which are essential for the functionality and construction of sub tubes by these organisms.