Final answer:
The answer to the fill-in-the-blank question is B) gene, chromosome, alleles. Alleles are different versions of a gene, and a gene is located on a specific locus on a chromosome. Population genetics studies the variety and distribution of alleles within a population.
Step-by-step explanation:
The correct answer to the student's question is B) gene, chromosome, alleles. A gene is a segment of DNA that is located on a chromosome and is responsible for a particular trait. A locus is the specific location on a chromosome where a gene is found. A gene can exist in different forms, which are called alleles. These alleles represent the variations in the DNA sequence for a particular gene, and they can result in different traits within a population. For example, the ABO blood type gene has three possible alleles which determine the type of blood-type protein present on the surface of red blood cells.
In population genetics, it's important to understand that while an individual can have only two alleles for each gene (one from each parent), the population as a whole can have multiple alleles for that same gene, providing genetic diversity. This diversity is a crucial component of evolution, as it gives a population the potential to adapt to new environments or changes over time.