Carbon is essential to life on Earth. One reason it is so vital is that it is able to form bonds with many other elements and with itself. Inside living things, there are many compounds based on carbon, including fats, sugars, starches, and oils. There are four main types of carbon compounds: carbohydrates, lipids, proteins, and nucleic acids. Each of these has important roles in living organisms. Proteins make up muscles and carry messages, and carbohydrates give cells energy.

Question

What is the meaning of the word "vital" in the passage?

A
Necessary

B
Small

C
Energetic

D
Useless

Answer 1

A. Necessary