If a cell transcribed and translated a gene’s intron by mistake, the most appropriate response would be:
Additional amino acids would be inserted into the chain.
Introns are non-coding sequences that are typically spliced out during mRNA processing before translation. If an intron were mistakenly included in the mRNA and translated, it could lead to the incorporation of additional (and often non-functional) amino acids into the resulting protein, potentially disrupting its normal function.