Which of the components of nucleolus disappears during late prophase and reappears during telophase?

The correct option is Nucleolus.

During the cell division cycle (mitosis), the cell undergoes a series of highly regulated phases to ensure the accurate distribution of genetic material. Let us break down the behavior of the nucleolus step-by-step through these stages to understand why it disappears and reappears:
1. Structure and Function: The nucleolus is a dense, membrane-less sub-nuclear structure where ribosomes are assembled. It is primarily made of RNA and proteins, associated with specific chromosomal regions called Nucleolar Organizer Regions (NORs).
2. Late Prophase Disappearance: As a cell exits interphase and enters prophase, chromosomes begin to condense tightly to facilitate safe segregation. Because the DNA is packed extremely tightly, the transcription of ribosomal RNA (rRNA) at the NORs is halted. Without active transcription and the association of nucleolar proteins, the nucleolus structurally disassembles and vanishes from view by late prophase.
3. Telophase Reappearance: Once the separated chromosomes reach the opposite poles of the cell during telophase, they begin to decondense back into their diffused chromatin state. This allows transcription of rRNA to resume at the NORs. As a result, nucleolar proteins and RNA reassemble, and the nucleolus becomes visible again in the newly forming daughter nuclei.