Identify the incorrect match between the alga and its respective class.

Step-by-step solution

Volvox is a green alga belonging to the class Chlorophyceae. Dictyota is a brown alga belonging to the class Phaeophyceae. Porphyra is a red alga belonging to the class Rhodophyceae. Sargassum is a brown alga belonging to the class Phaeophyceae, not Rhodophyceae. Therefore, the match for Sargassum is incorrect. Answer: Sargassum - Rhodophyceae