Dna exists in tight coils called a.)genes b.)bases c.)chromosomes d.)mutations

C). Chromosomes

Explanation:

Deoxyribonucleic acid (DNA) is the stored form of the genetic material in most living organisms. DNA is a nucleic acid composed of two polynucleotide chains. It contains the genetic information needed by the organism for its life processes.

However, the DNA is too long to fit into most cells. The cell then devises a means to allow its genetic material fit into its cell. The DNA is coiled around the core of a set of proteins called HISTONES to form a structure known as NUCLEOSOME. The nucleosome is further wrapped around these HISTONES to form another structure called CHROMATIN. The Chromatin then undergoes condensation during cell division to form the X-shaped structure called CHROMOSOME.

The oxygen and hydrogen atoms in a water molecule are held together by a covalent bond. This means that the electrons from the oxygen and hydrogens go around all three atoms instead of just the atom they started with. To form a covalent bond, the oxygen and hydrogen atoms share several electrons.