Which element is considered the most versatile element in living organisms and why?
hydrogen, because it is a key component in organic molecules and provides most of the mass of human bodies
hydrogen, because it can be found in both organic and inorganic molecules
carbon, because it can bond with many elements to form complex molecules
carbon, because it provides strength to the important protein, keratin

Answer;

-Carbon, because it can bond with many elements to form complex molecules.

Explanation;

-A compound found mainly in living things is known as an organic compound. Organic compounds make up the cells and other structures of organisms and carry out life processes. Carbon is the main element in organic compounds, so carbon is essential to life on Earth.

-Living things need carbon in order to live, grow, and reproduce. Carbon is a finite resource that cycles through the Earth in many forms. This makes carbon available to living organisms and remains in balance with other chemical reactions in the atmosphere and in bodies of water like ponds and oceans.

the answer to your question is:

c. complementary base-pairing