Introduction:
Linked genes are genes that are located close to each other on the same chromosome. They tend to be inherited together, meaning they are often passed on as a unit. The degree of linkage between two genes is influenced by their distance from each other on the chromosome. In this case, we are looking at the linked genes HBA1 and HBA2 and their location on a specific chromosome.

Explanation:
The genes HBA1 and HBA2 encode for the alpha chains of hemoglobin, a protein responsible for oxygen transport in red blood cells. These genes are located on chromosome 16 in humans.

Chromosome 16:
Chromosome 16 is one of the 23 pairs of chromosomes found in humans. It is a medium-sized autosome, meaning it is not involved in determining an individual's sex. Chromosome 16 contains approximately 90 million base pairs and is estimated to contain around 2,000 genes.

HBA1 and HBA2:
The HBA1 and HBA2 genes are located in a region of chromosome 16 called the alpha-globin gene cluster. This cluster also includes other genes involved in the production of alpha globin chains, such as HBA-T1 and HBA-T2. The alpha globin chains combine with beta globin chains to form adult hemoglobin (HbA), the predominant type of hemoglobin in adults.

Linkage:
Since HBA1 and HBA2 are located close to each other on chromosome 16, they are considered to be linked genes. The degree of linkage between these genes can vary depending on the distance between them. If the genes are very close together, they are more likely to be inherited together. If they are farther apart, the chance of recombination occurring between them is higher.

Conclusion:
In summary, the linked genes HBA1 and HBA2 are located on chromosome 16 in humans. These genes are part of the alpha-globin gene cluster, which plays a crucial role in the production of alpha globin chains. Understanding the location and linkage of these genes is important for studying genetic disorders related to hemoglobin production and transport.

Option D-16