The nucleic acid that contains the genetic part of a cell is deoxyribonucleic acid (DNA).

Here's why:

* DNA carries the genetic code: DNA contains the instructions for building and maintaining an organism. These instructions are encoded in the sequence of its nucleotide bases (adenine, guanine, cytosine, and thymine).

* DNA is passed down: DNA is passed from parent to offspring, ensuring the continuity of genetic information across generations.

While RNA (ribonucleic acid) is also a nucleic acid, it plays a different role. RNA is involved in the process of protein synthesis, using the instructions from DNA to create proteins.