The physical location of a gene on a chromosome is called

A) an allele.
B) its locus.
C) a trait.
D) a chromatid.
E) its genotype.

Chromosome

A thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Locus

(pl., loci) The place on the chromosome at which the gene for a given trait occurs (i.e., a segment of the chromosomal DNA containing information that controls some feature of the organism); also called gene locus.