Covalent bonds between nucleotides in DNA are found between:

A) a phosphate group and a nitrogenous base.
B) a sugar and a nitrogenous base.
C) nitrogenous bases.
D) phosphate groups.
E) a sugar and a phosphate group.

To determine the correct answer, we need to understand the structure of a nucleotide in DNA. A DNA nucleotide consists of a sugar molecule, a phosphate group, and a nitrogenous base.

In a DNA molecule, the covalent bonds connect the sugar molecules and phosphate groups, forming the backbone of the DNA strand. Specifically, the covalent bond exists between the 3' carbon atom of the sugar molecule and the 5' carbon atom of the adjacent sugar molecule, creating a sugar-phosphate backbone.

However, the nitrogenous bases are connected to the sugar molecule through a different type of bond known as a hydrogen bond. These hydrogen bonds are responsible for holding the two DNA strands together in a double helix structure.

Based on this information, we can conclude that the correct answer is:
B) a sugar and a nitrogenous base.