Answer:
Step-by-step explanation:
A female human has 46 chromosomes, which are arranged in 23 pairs. One chromosome of each pair is inherited from the mother and the other is inherited from the father.
In a female, one of the chromosomes in each pair is an X chromosome, while the other chromosome can be either an X chromosome or a Y chromosome. This results in a total of two X chromosomes in a female and one X and one Y chromosome in a male.
Therefore, if the lab worker counted 23 pairs of chromosomes and observed two X chromosomes, she could conclude that the chromosomes come from a female.