The function of nucleolus is to make:

Explanation

The nucleolus is a key subcompartment within the cell nucleus responsible for producing ribosomes. It achieves this by transcribing ribosomal RNA (rRNA) from rDNA templates and assembling it with proteins to form ribosomal subunits. These subunits are then transported to the cytoplasm to become functional ribosomes, which are critical for protein synthesis. Option A (rDNA) is incorrect because rDNA is the template for rRNA, not a product of the nucleolus. Option B (RNA) is too general as the nucleolus specifically synthesizes rRNA, not all RNA types. Option D (Chromosomes) is incorrect since chromosomes are DNA structures, not synthesized by the nucleolus.