B. by the sharing of electrons
Answer choices A and C are incorrect because covalent bonds form as a result of electrons (protons are kind of irrelevant). Answer choice D is incorrect because it describes an ionic bond.
Further study topics: water polarity, hydrogen bonds, free radicals, valence electrons, and more!
Answer:
c
Explanation:
Gas exchange. Gas exchange occurs as a result of respiration, when carbon dioxide is excreted and oxygen taken up, and photosynthesis, when oxygen is excreted and carbon dioxide is taken up. The rate of gas exchange is affected by: the area available for diffusion.
Answer:
The crust
Explanation:
The solid, outer layer is called the crust.