Question

which best describes a gene?
the short arm of a chromosome
tightly coiled strands of dna
the center of a chromosome
a segment of chromosomal dna

Explanation:

A gene is defined as a segment of DNA that contains the instructions for making a specific protein or performing a particular function. Chromosomal DNA is made up of many genes. The short arm of a chromosome is just a part of the chromosome structure. Tightly coiled strands of DNA refer to chromosomes themselves (as chromosomes are made of coiled DNA). The center of a chromosome (centromere) is a structural part, not a gene.

Answer:

a segment of chromosomal DNA