Answer: The correct answer is- b) Cyanobacteria ( also known as blue green algae).
Cyanobacteria ( blue green algae) are the aquatic, photosynthetic bacteria that utilize carbon dioxide and water in the presence of sunlight to produce food ( glucose) and release oxygen in the environment.
This process is known as photosynthesis.
They use a light harvesting green colored pigment called chlorophyll- a, which is present in them.
Thus, scientist use cyanobacteria to eat carbon dioxide.