Which of the following is not a method of chromosomal sex determination that occurs in nature?
a. In birds, the mother's sex chromosomes determine the sex of the offspring.
b. In sea turtles, eggs laid in hot sand become females and eggs laid in cooler sand become males
c. In humans, the presence of a Y chromosome makes an individual male, even if he also possesses two X chromosomes.
d. In bees, the eggs that the queen allows to be fertilized become females and the eggs she doesn't fertilize become males.
e. All of the above are naturally occurring examples of sex determination.