Which structure is present within a chromosome?

Ribosomal $RNA$ is actively synthesized in

Genes are located in.....

$A$ normal metaphase chromosome with a medial centromere is:

The shape of chromosomes can be identified by which of the following?

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.