When an 'X' bearing sperm fertilises the egg, the resulting zygote has the following combination of chromosomes :

In human beings, sex is determined genetically.

• Human somatic cells contain 23 pairs of chromosomes (total 46 chromosomes), consisting of 22 pairs of autosomes (44 autosomes) and 1 pair of sex chromosomes.
• Females have a pair of X chromosomes ($\text{XX}$), so all eggs (ova) carry one X chromosome ($22 + \text{X}$).
• Males have one X and one Y chromosome ($\text{XY}$), so sperms can be either X-bearing ($22 + \text{X}$) or Y-bearing ($22 + \text{Y}$).
• When an X-bearing sperm ($22 + \text{X}$) fertilises an egg ($22 + \text{X}$), the resulting zygote will have $(22 + 22) = 44$ autosomes and $(\text{X} + \text{X}) = \text{XX}$ sex chromosomes, giving a total combination of $44 + \text{XX}$ (female offspring).

• Option (a) $44 + \text{XX}$ is correct.
• Option (b) $44 + \text{XY}$ would result from fertilization by a Y-bearing sperm.
• Options (c) and (d) represent only 24 chromosomes, which is incorrect for a human diploid zygote (which must have 46 chromosomes).