Nucleolus plays important role in production of

Answer: Option A

The nucleolus plays important role in the production of rRNA.
The nucleolus is a prominent nuclear condensate that plays a central role in ribosome biogenesis by facilitating the transcription and processing of nascent ribosomal RNA (rRNA).
At the nucleolus, a long ribosomal RNA (rRNA) precursor molecule is transcribed from DNA, processed into three mature RNAs, and packaged together with specific proteins to make the large and small ribosomal subunits.