Explanation

Gonyaulax is a representative group of unicellular organisms, the Pyrrophyta (sometimes called Dinophyta). 

• This is a group of mostly marine plankton, and Gonyaulax is a well-known genus within this group.
• Dinoflagellates are known for their two flagella and can be bioluminescent.
• Some species can cause harmful algal blooms, commonly known as red tides.

Phaeophyta (Brown Algae):

• These are large, mostly marine algae, such as kelp and seaweeds.
• They are not related to Gonyaulax.

Chlorophyta (Green Algae):

• These algae are mainly freshwater organisms, and some live in marine environments.
• They are not related to Gonyaulax.

Chrysophyta (Golden Algae):

• These are mostly freshwater algae
• And they are distinct from Gonyaulax.