Final answer:
Eastern Subterranean termites feed along the grain in the softer parts of wood. They can digest wood due to mutualistic archaea in their guts, which produce enzymes that break down lignin, enabling termites to absorb nutrients from wood. Option B is correct.
Step-by-step explanation:
The termites that feed along the grain in the Springwood and softwood portion of the wood are known as Eastern Subterranean termites (Eastern Subs). These termites are particularly known for feeding on softwood and the Springwood sections of timber, which are softer and easier to digest due to their higher cellulose content.
Termites are able to digest wood because of a symbiotic relationship with microorganisms in their guts, specifically mutualistic archaea and other microorganisms that produce enzymes capable of breaking down lignin into soluble carbohydrates. The lignin is a complex organic polymer present in wood that contributes to its rigidity and resistance to decay. Without these microorganisms, termites would not be able to access the nutrients contained in wood.
The adaptations in the internal digestive organs of termites emphasize the importance of mutualism in nature. The relationship between termites and their gut microorganisms allows these insects to thrive on a diet that consists exclusively of wood, an incredible feat considering that wood is a difficult substance for most organisms to decompose and utilize as a food source.