The correct answer is d) Translation.
To explain, the nucleus is the cellular organelle where several key processes of gene expression occur. Transcription, the process of copying DNA to produce RNA, happens in the nucleus. Following transcription, splicing, which is the modification of the RNA transcript to remove non-coding sequences (introns), also takes place there. Polyadenylation, the addition of a poly-A tail to the RNA molecule, occurs in the nucleus after transcription and splicing.
On the other hand, translation, which is the process of synthesizing proteins from mRNA, occurs in the cytoplasm, specifically on ribosomes. Therefore, translation is the only option among the four that does not occur in the nucleus.