Before the onset of pubey, the GnRH neurons are under the inhibitory control of:

The transition to a reproductive state (during pubey) requires maturation of the entire hypothalamic-pituitary-gonadal axis. Before this maturation occurs, plasma LH and FSH levels are diminished despite low concentrations of gonadal steroids and inhibin. GnRH neurons are said to be under inhibitory influence of GABAergic neurons. Additional inhibition comes from NPY, endorphins, and nocturnal melatonin secretion. Hence, option C is more appropriate.