Final answer:
Nonsense-mediated decay is the mechanism that destroys messenger RNAs containing premature stop codons to prevent the production of non-functional proteins.
Step-by-step explanation:
The mechanism responsible for destroying messenger RNAs containing premature stop codons is called nonsense-mediated decay (C). This process helps to prevent the production of non-functional or truncated proteins. When a premature stop codon is encountered during translation, the mRNA molecule is recognized and degraded, ensuring that only functional proteins are synthesized.