The complicated molecules that make up living things usually contain

carbon. Why is carbon so important in these molecules?

The carbon atom is capable of forming four covalent bonds in combination with other elements as hydrogen, oxygen, nitrogen, sulfur, phosphorous and halogens. The compounds formed are called organic molecules which because of the nature of the chemical bond are stable compounds.

Adding an amino group - NH₂ and a carboxylic group - COOH to a carbon chain containing carbon and hydrogen we form amino acids. Condensation of amino acids will form peptides and further proteins, which are chemical molecules from which living things are made.

Carbon is the backbone of the molecules from which life is made.

Answer;

A. Carbon can form four strong covalent bonds.

Explanation;

Carbon can form up to 4 covalent bonds, and it can form reasonably strong bonds with nitrogen, oxygen, and other heteroatoms.

Carbon also has an almost unique ability to catenate: to form long chains with

C - C linkages, and along the chain there can be regions of different reactivity (by the presence of functional groups).