Final answer:
The three most common ways that the function of a tumor-suppressor gene is lost are mutation within the gene, loss of the chromosome that carries the gene, and abnormal DNA methylation near the gene's promoter. The options (1), (2) and (3) are correct.
Step-by-step explanation:
The three most common ways that the function of a tumor-suppressor gene is lost are:
- Mutation within the gene
- Loss of the chromosome that carries the gene
- Abnormal DNA methylation near the gene's promoter
These genetic changes can disable tumor-suppressor genes, leading to uncontrolled cell division and the development of cancer. Therefore, options (1), (2), and (3) are correct.