Non-membranous nucleoplasmic structures in the nucleus are the site for active synthesis of:

$A$ : The nucleus of a plasma cell has a cart-wheel appearance.
$R$ : The nucleus contains peripheral clumps of heterochromatin.

The double-layered tubular structure present in the nucleus is:

Polytene chromosomes in the salivary glands of Drosophila are formed as a result of:

Which of the following is present in a higher amount in the nucleus but in a lower amount in the chromosome?

Which of the following statements is/are correct?
$(a)$ The nuclear matrix or nucleoplasm contains the nucleolus and chromatin.
$(b)$ The outer nuclear membrane $(Ectokaryotheca)$ is usually continuous with the endoplasmic reticulum and also bears ribosomes on it.
$(c)$ Cells that are actively synthesizing protein have small and fewer nucleoli.