The correct option is A Uniflagellate gametes - Polysiphonia
Polysiphonia , which belongs to the red algae, produce non-motile gametes.
The biflagellate zoospores of brown algae help in the asexual reproduction.
Gemma cups are formed during the asexual reproduction of the bryophtyes like Marchantia.
Chlorella is a genus of single-celled green algae.