Question

ecologists use quadrats because: *
its impossible to count every organism
theyre used only for large animals
it provides exact counts, not estimates
they cant use graphs

Explanation:

Quadrats are used in ecology for sampling. In large areas, it's impractical to count every organism. Quadrats allow ecologists to sample a representative area and estimate population sizes. They are not just for large animals (can be used for plants, small organisms too). They give estimates (not exact counts as it's a sample). And the reason isn't about not being able to use graphs.

Answer:

It's impossible to count every organism