Which of the following genes typically acts as a tumor suppressor, requiring inactivation of both alleles for its oncogenic effect?

✓ Correct Answer: Option C

BRCA1 is a classic tumor suppressor gene, following Knudson's 'two-hit' hypothesis, where both copies must be inactivated for increased cancer risk. MYC, RAS, and HER2 are oncogenes, typically requiring only one mutated allele.