Question

a population limiting factor in plants and algae we have mentioned a lot in class is predatory speed. availability of nitrogen. lack of darkness.

Explanation:

Nitrogen is an essential nutrient for plants and algae. Its limited availability can restrict their growth and reproduction, acting as a population - limiting factor. Darkness is not a typical limiting factor as they can adapt to different light conditions, and predatory speed does not directly limit plant and algal populations in the same way as nutrient availability.

Answer:

availability of nitrogen.