The answer is copper. Nonrenewable resources are those that cannot be readily/naturally replaced at rates that match those of consumption (an aspect that allow renewable resources to be sustainable). Copper are made deep in earth at very slow rates hence do not readily renew themselves. Organisms, on the other hand die, and are naturally replaced by offspring.
Humans out here just eating meat and driving cars. Playa don’t hate
You should be changing the amount of water because the question isn't asking for temperature, amount of light, nor the amount of soil. You would be changing the amount of water because that is what you are experiment for.