Answer:
a. significantly lesser
Step-by-step explanation:
The density of protists living in the hay infusion is significantly lesser than the regular pond water because protists likes to live in aquatic or any water bodies. Some protists float on the surface of the water making their own food like plants by using the process of photosynthesis. Aquatic environments are ideal environment for protists, which have cilia and flagella that allows them to move in the water in search of food..