Context: Read the passage. Then answer the question.

Termites are small insects that eat wood. But they cannot completely digest the wood on their own. To help digest the wood, some termites rely on organisms called protists that live in their guts. These protists are microscopic, or too small to see without the aid of a microscope.
When the protists digest the wood, they get energy and nutrients. Without protists in its gut, a termite would not be able to use wood for food, so it would starve to death.
Figure: a termite eating dead wood.
Which type of relationship is formed when protists live in a termite's gut?
A. mutualistic
B. parasitic
C. commensal
Identify the correct option from the choices provided and respond with the letter of the correct option.

A