In humans, sex is determined by
- two homologous chromosomes
- a dominant gene for maleness present in a male
- two similar sex chromosomes in the male and dissimilar in the female
-
the differences in the nature of the X and Y chromosomes in the male.
The correct answer is: D
Explanation
In humans, sex is determined by the difference in the nature of the X and Y chromosomes in males. Females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY). The presence of the Y chromosome determines maleness because it carries the SRY gene, which triggers the development of male characteristics. The X chromosome carries genes related to both male and female sexual development.