Answer:
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.
The answer would be (b) evolutionary species concept.
It is indeed A, all of the other answers would be examples of how not to conserve non-renewable resources
D. Plants have adapted to deal with the sun in many different ways, and this is one. The stomata are regulated by guard cells, which are activated by different things depending on the species of plant, and guard cells are supposed to keep the stomata from staying open all the time and losing too much water to evaporation. So, the solution is to have the stomata on the bottom of the leaf to prevent direct sunlight contact (and therefore more evaporation), and guard cells to protect the stomata.
