Dark Stage.
At the light stage, sunlight is absorbed by the chlorophyll to be converted into Chemical energy.
Water will be broken down into H+ ions and OH- ions in the presence of light.
At dark stage, sugars are synthesised from carbon dioxide.
The answer is the second choice: variation, overpopulation, adaptation
Your answer is B weathering, deposition, and erosion :D i really hope i helped you!
Because the chain will begin to shut down and will no longer pump [H+] (hydrogen ions) across the membrane; thus, the proton gradient can not be maintained.
:) I hope this answers your question!