Answer:
I think you're referring to the Metaphase...
Explanation:
During Cell Division (or, rather before!) the DNA needs to be replicated. This normally is done by DNA Polymerase, and results in two identical double strands (the "Sister Chromatids".
These chromatids are held together at the Centromere, which will be the heart of the "X"-shape. After that the DNA is packed into Chromosomes by winding it around proteins called Histones. If I remember correctly there are 5 different Histones.
This "Zipping Up" makes the chromosomes more visible.
As the two sister chromatids are still connected, the result is the X-shaped Metaphase Chromosome....
I think it’s A, begins to change :))
The most important acid deoxyribonucleic acid, or DNA, which carries the genetic code of any organism it, and the way that it transmits the individual characters in the life without this acid, or genetic code world would not exist :)
I hope you understand what I mean :)