Infertility can occur in both the sexes due to deficiency of

The correct option is D FSH

FSH (Follicle stimulating hormone) is secreted from anterior lobe of pituitary gland. In females, it stimulates development of ovarian follicles upto ovulation and in males, it stimulates development of seminiferous tubules and spermatogenesis (formation of sperms from germ cells). Deficiency of FSH can lead to failure of ovulation in females and spermatogenesis in females. Thus, infertility can occur.

So, the correct answer is 'FSH'.