Final answer:
Hydrogen is the most important element in the H.T.S. and is abundant in the universe. It is a component of many compounds and essential for various substances found on Earth.
Step-by-step explanation:
Hydrogen is the most important element in the H.T.S. (Hydrogen TS). Hydrogen is the most abundant element in the universe and the sun and other stars are largely composed of it. It is a component of many compounds found on Earth, including water and petroleum. Hydrogen is also an essential part of numerous minerals, cellulose, sugars, fats, and acids.