**Core Concept**
The BRCA-1 gene is a tumor suppressor gene that plays a crucial role in maintaining genomic stability by repairing DNA damage. Mutations in the BRCA-1 gene are associated with an increased risk of breast and ovarian cancers.

**Why the Correct Answer is Right**
The BRCA-1 gene is located on the long arm of chromosome 17, specifically at the q21 band. This location is significant because it allows the gene to be inactivated by mutations, leading to cancer development. The BRCA-1 gene encodes a protein called breast cancer type 1 susceptibility protein, which is involved in the repair of DNA double-strand breaks through homologous recombination.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct chromosome number.
**Option B:** This option is incorrect because it does not provide the correct arm of the chromosome where BRCA-1 is located.
**Option C:** This option is incorrect because it does not specify the correct band of the chromosome where BRCA-1 is located.

**Clinical Pearl / High-Yield Fact**
The BRCA-1 gene is a classic example of a tumor suppressor gene, and mutations in this gene can lead to cancer development. It is essential for clinicians to understand the genetic basis of cancer to provide accurate genetic counseling to patients.

**Correct Answer: D. 17**