Genetic screening is a diagnostic test to identify the presence or absence of changed genes.

• A. The presence of metabolic disorders
• B. The size of the genome
• C. The presence or absence of changed genes
• D. The expression level of a gene

Answer: (C)

Genetic screening focuses on examining the DNA to see whether a gene has changes or mutations. It aims to determine the presence or absence of altered genes, which is exactly what the statement describes. This is different from tests that look for metabolic disorders, which rely on biochemical measurements rather than checking gene sequences. It’s also not about genome size, which doesn’t vary in a way that would be useful to screen for gene changes, and not about how much a gene is being expressed, which reflects activity rather than whether the gene itself has changed.