In most animals,sex of the offspring is established during :

Most animals are

Sex of the offspring depends on the fertilizing ovum in

Sex of the offspring depends on the fertilizing ovum in

Which of the two, sperm or ovum determines the sex of the offsprings in fowl? Justify your answer.

In turtle, high incubation temperature leads to the development of female offspring. On the other hand in lizards, high incubation temperature leads to the development of male offspring. What determines the sex of the offspring in these examples?