Which of the following monomers would be used to make the double helix of a dna molecule?
a monomer made up of a nitrogenous base, a five-carbon sugar, and a phosphate group bonded together.
a monomer with an amino group, carboxylic acid, hydrogen atom, and r group bonded to a central carbon atom.
a monomer with the formula c6h12o6. five carbon atoms and one oxygen atom form a hexagonal ring, with the other atoms bonded to that ring.
a molecule made up of four carbon rings with other atoms bonded to those rings.

Answer;

A monomer made up of a nitrogenous base, a five-carbon sugar, and a phosphate group bonded together.

Explanation;

-Nucleic acids such as DNA and RNA are made up of chains of many repeating units called nucleotides. Nucleotides are made up of a 5-carbon sugar(deoxyribose),a phosphate group and a nitrogenous base bound to the sugar . Adenine makes two bonds with Thyamine whereas Cytosine makes three bonds with Guanine.

-The DNA double helix is held together by two types of bonds, covalent and hydrogen. Covalent bonds occur within each linear strand and strongly bond the bases sugars, and phosphate groups.  Hydrogen bonds occur between the two strands and involve a base from one strand with a base from the second in complementary pairing. These hydrogen bonds are individually weak but collectively quite strong.

this process is called "phosphorylation." a phosphate bond joins adenosine diphosphate to form adenosine triphosphate.