Monica's ultrasound reveals that the baby she is carrying is a boy. which chromosome pair is present in her baby?

XY

A human baby’s gender is determined by the sperm that fertilises the egg cell. A chromosome from the sperm cell which is either X or Y, fuses with the X chromosome in the egg cell. The baby will be a girl if an X chromosome fuses with the X chromosome in the egg cell or it will be a boy if a Y chromosome fuses with the X chromosome in the egg cell which means the females carry XX, and the males carry XY. From the question above, Monica is carrying a boy so the XY chromosome pair is present in her baby.