Explanation

Cross-checked against the CDS 2023-1 answer keys (examzy, prepp, oswaal): the correct option is D. RNA is synthesised in the nucleus (mRNA, tRNA, rRNA), functions in the cytoplasm (translation), is encoded by the separate genomes of mitochondria and chloroplasts (organellar RNAs), and forms the structural core of ribosomes as rRNA. The endoplasmic reticulum is merely a membrane system — RNA is associated with it only via bound ribosomes — so option C is wrong. The file had no stored key (null); it is corrected to D.