A Bird Species Nests in a Specific Kind of Tree

Multiple Choice

A bird species nests in a specific kind of tree. The tree is not harmed by the bird building its nest in the tree's branches, but the bird benefits from the shelter provided by the tree and is better able to successfully raise young. This is an example of

A) mutualism.
B) endosymbiosis.
C) commensalism.
D) symbiosis.