If a cell transcribed and translated a gene's intron by mistake, the most accurate response would be:
Additional amino acids would be inserted into the chain.
This is because introns are non-coding regions of the gene that are normally spliced out during RNA processing. If an intron is incorrectly included in the final mRNA and translated, it could lead to the incorporation of non-standard sequences into the protein, likely resulting in a nonfunctional or malfunctioning protein.