Hypertonic solutions have water potential.

The best answer is C.

What may happen as plants gradually die out would be an imbalance of the atmospheric air with oxygen getting depleted and carbon dioxide levels gradually increasing. Plants are the only living things that consume the carbon dioxide that we breathe out and in turn give out oxygen that we breath in on for life.

In reality, plants are such  a vital and integral part of the ecosystem that without them  life on earth would not even be possible. Plants are the backbone of all life. They make oxygen, are the source of all food directly or indirectly, and they regulate the water cycle by  helping  to distribute and purify the planet's water.