Answer:
Your answer would be A. GENES
Explanation:
A variation is a reference to the differences or deviations, such as the structure and form, as for crossing over is the exchange of genetic material between the non-sister chromatids of the homologous chromosomes during meiosis.
The number 45 means that the subject has 44 normal autosomal chromosomes (22 chromosomes pairs) plus one (1) good sex chromosome (out of the normal homologous pair). The X0 means that the subject, usually a female, lacks one sister chromosome of the homologous X chromosome pair, or has a partial X sister chromosome.
