The correct reason for the low occurrence of haemophilia in women is option 2. Haemophilia is not dominant in genes and found in Y-Chromosomes, as stated in option 1. Haemophilia is a recessive genetic disorder, meaning it requires two copies of the faulty gene (one from each parent) to be present for the disorder to be expressed. Haemophilia is not specific to the Y-Chromosomes and can occur in individuals with any combination of sex chromosomes.

Option 3 is also incorrect. While it is true that women have a pair of X-Chromosomes in their genes, having two X-Chromosomes does not provide protection against haemophilia. If a woman inherits a faulty gene for haemophilia on one of her X-Chromosomes and a normal gene on the other X-Chromosome, she will be a carrier of the disorder and can pass it on to her children.

Therefore, only option 2 provides the correct explanation for the low occurrence of haemophilia in women.