This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transcription, Subject name: Biochemistry
At which of the following levels the predominant regulation of gene expression of both prokaryotes and eukaryotes take place? 
Select and explain. 
A. DNA replication, B. Transcription, C. Translation, D. Post-translational
B: Transcription
Answer: B: Transcription 
Explanation: Expression of a functional gene product from genes is the gene expression. The functional product is not always proteins. Non-protein coding genes are also expressed as functional RNAs (tRNA, snRNA, miRNA etc.) Regulation of gene expression occurs at transcriptional level in both prokaryotes and eukaryotes.