Sex in human embryo is determined by:

'X' or 'Y' chromosome of sperm

The correct answer is Option (2) –'X' or 'Y' chromosome of sperm

Sex determination in human embryos is based on the combination of sex chromosomes inherited from the parents. Humans have two types of sex chromosomes, X and Y:

• Females have two X chromosomes (XX).
• Males have one X and one Y chromosome (XY).

Here’s how sex determination works during fertilization:

Egg Cell (Ovum):

• The egg cell from the mother always contributes an X chromosome because females only have X chromosomes (XX).

Sperm Cell:

• The sperm cell from the father can contribute either an X chromosome or a Y chromosome because males have both X and Y chromosomes (XY).

Fertilization:

• If the sperm carrying an X chromosome fertilizes the egg (X), the resulting embryo will have two X chromosomes (XX) and will develop into a female.
• If the sperm carrying a Y chromosome fertilizes the egg (X), the resulting embryo will have one X and one Y chromosome (XY) and will develop into a male.

Therefore, the sex of the human embryo is determined by whether the sperm carries an X or a Y chromosome.