Which of the following is true for nucleolus ? a. It takes part in spindle formation.
b. It is a membrane - bound structure.
c. Larger nucleoli are present in dividing cells.
d. It is a site for active ribosomal RNA synthesis.

d. It is a site for active ribosomal RNA synthesis.

Explanation:

The nucleolus is a region in the nucleus of eukaryotes. It is very obvious region of the nucleus as it occupies the largest part of the nucleus. The nucleolus contains RNA and it produces ribosomal RNA or rRNA from it.

It is not a membrane-bound and functions majorly in the synthesis of ribosomal RNA. In essence, they are a site for active ribosomal RNA synthesis. The subunits of the ribosomes are synthesized in the nucleolus when ribosomal RNA combine with proteins before they are finally ejected from the nuclear region to become ribosomes.