Which of the following undergoes spermiogenesis?

Which cells provide nutrition to the developing spermatozoa during spermatogenesis?

The mother germ cells are transformed into a mature follicle through a series of steps. Provide the missing steps in the blank boxes.
$\boxed{\text{Oogonia}} \to \boxed{A} \to \boxed{\text{Primary follicle}} \to \boxed{B} \to \boxed{C} \to \boxed{\text{Mature or Graafian follicle}}$

The second maturation division of the mammalian ovum occurs:

Androgen binding protein,which helps in concentrating testosterone in the seminiferous tubule,and which inhibits $ICSH$ secreted by the anterior pituitary and $GnRH$ production by the hypothalamus,is secreted by:

Polar bodies are formed during