Answer: A. Transcription uses a gene’s DNA sequence to synthesize mRNA. If transcription of gene X is switched off, new mRNA from that gene is not produced; translation uses mRNA to synthesize a polypeptide.
B: confuses transcription with translation by using DNA directly as the template for polypeptide synthesis.
C: confuses gene expression with DNA replication; switching off transcription does not itself prevent DNA copying.
D: confuses transcriptional control with translational control; existing mRNA can still be translated.
Remember: transcription makes mRNA; translation makes a polypeptide from mRNA.