Answer:
What Are the Lungs and Respiratory System? The lungs and respiratory system allow us to breathe. They bring oxygen into our bodies (called inspiration, or inhalation) and send carbon dioxide out (called expiration, or exhalation). This exchange of oxygen and carbon dioxide is called respiration.
Explanation:
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!
