What is the reason carbon atoms are the most versatile building blocks of the molecules used by living organisms?

Explanation:

Atomic number of carbon is 6. So, 4 valence electrons are present.

Therefore, it can form 4 covalent bonds with varying bond angles by sharing its valence electrons.

Catenation is also an important property of carbon. Catenation is bonding with atoms of same element. Carbon skeleton can be formed in any direction and can vary in length, branching, and ring structure.

Elements required for making most of the molecules in living organisms are:

C, H, N, O, P and S

Carbon easily form covalents with other 5 elements.

These properties make carbon most versatile building blocks of the molecules used by living organisms.

its first and third is your answer i did the qustion the fourth isnt right

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.