Question

how many times does all matter in an ecosystem have to be used?
repeatedly
five times
occasionally
only once

Explanation:

In an ecosystem, matter is recycled. Nutrients and other materials are continuously reused through biogeochemical cycles (like the carbon cycle, nitrogen cycle). This recycling means matter is used repeatedly. For example, carbon is taken up by plants during photosynthesis, passed to animals when they eat plants, released back to the atmosphere when organisms respire, and then taken up again by plants. So matter in an ecosystem is used repeatedly.

Answer:

A. repeatedly