Biology

The correct answer is: D.Mutualism.

In this relationship:

1.The algae provide food for the fungus, typically through photosynthesis, which the fungus can use as a nutrient source.

2.The fungus provides a suitable living environment for the algae by offering protection and a stable surface to grow on, such as on rocks or tree bark. The fungus can also help retain moisture,

which benefits the algae.

This is a mutualistic relationship because both the algae and the fungus benefit from the interaction:

The algae get a protected environment in which to grow.

The fungus gets a nutrient source (food) from the algae. ...