Doubling of chromosome occurs in

Solution (By Examveda Team)

The correct answer is Option C: Anaphase

Here's why:

* Chromosomes are doubled during the S phase (Synthesis phase) of interphase, before mitosis even begins.

* However, the *separation* or *doubling of the chromosome number* we observe happens in Anaphase. During Anaphase, the sister chromatids (which are the two identical copies of each chromosome) are pulled apart to opposite poles of the cell.

* So, while the genetic material (DNA) has been replicated already, it's in Anaphase that the cell goes from having each chromosome as a duplicated structure (sister chromatids) to having each sister chromatid becoming its own, independent chromosome, effectively doubling the chromosome number at each pole.

Let's look at why the other options are incorrect:

* Prophase: This is when the chromosomes condense and become visible. They are already doubled (as sister chromatids) but are not yet separated.

* Metaphase: The chromosomes line up in the middle of the cell, still as sister chromatids.

* Telophase: The chromosomes arrive at the poles of the cell, and the nuclear envelope reforms around them. They have already been separated in Anaphase.

Therefore, Anaphase is the stage where the *number* of chromosomes effectively doubles because the sister chromatids separate and become independent chromosomes.