Which process is significant for evolution?

Which of the following statements are correct regarding the importance of meiosis?
$(i)$ It increases the genetic variability in the population of organisms from one generation to the next.
$(ii)$ It decreases genetic variability.
$(iii)$ It occurs in all cells of our body.
$(iv)$ It is an important process for evolution.

Which process is essential for maintaining a constant and specific number of chromosomes in organisms across generations?

$X -$ It is very important for the process of evolution.
$Y -$ Crossing over is the exchange of genetic material between two homologous chromosomes.

In which of the following stages does the centromere not split?

State the significance of meiosis.