Isogamous condition with nonflagellated gametes is found in (a) Volvox (b) Fucus (c) Chlamydomonas (d) Spirogyra.
Option D Chlamydomonas has flagellated gametes which are similar or dissimilar in size. In Volvox and Fucus, nonmotile female gametes and motile male gametes are produced (oogamy). Spirogyra has gametes that are similar in size (isogamous) and are nonflagellated.
