Using the conventional three-way distinction between isogamy, anisogamy and oogamy, identify an alga that exhibits anisogamy.

Explanation

In the conventional three-way distinction, Eudorina illustrates anisogamy with unequal-sized motile gametes, while Volvox illustrates oogamy with a large non-motile egg. In broader terminology oogamy is a specialized form of anisogamy; the classification convention is therefore made explicit.