Question

algae being held in place by a fungus...together they are called a lichen. algae feeds the fungus nutrients that it creates through photosynthesis while the fungus holds the algae in place so that it can gather the sunlight to perform photosynthesis in the first place. alice the algae and fred the fungus took a lichen to each other.
mutualism
parasitism
commensalism

Explanation:

Mutualism is a symbiotic relationship where both organisms benefit. In lichen, algae provide nutrients via photosynthesis and fungus provides a structure for sunlight - gathering. Parasitism is when one organism benefits at the expense of the other, and commensalism is when one organism benefits and the other is neither helped nor harmed.

Answer:

A. mutualism