This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetic Basics Of Carcinogenesis, Subject name: Pathology
A 2-year-old boy is found to have bilateral retinal tumors. Molecular studies demonstrate a germline mutation in one allele of the Rb gene. Which of the following genetic events best explains the mechanism of carcinogenesis in this patient? 
Select and explain. 
A. Balanced translocation, B. Expansion of trinucleotide repeat, C. Gene amplification, D. Loss of heterozygosity
D: Loss of heterozygosity
Answer: D: Loss of heterozygosity 
Explanation: Retinoblastomas are malignant ocular tumors of young children. In cases of hereditary retinoblastoma:- An affected child inherits one defective Rb allele together with one normal gene. This heterozygous state is sufficient to prevent the development of retinoblastoma. However, if the remaining normal Rb allele is inactivated by deletion or mutation, the loss of its suppressor function leads to the appearance of a neoplasm. This genetic process is referred to as loss of heterozygosity. Diagnosis: Retinoblastoma