Statement Assertion A states that "FSH acts upon ovarian follicles in female and Leydig cells in male." To analyze this, we need to examine the role of FSH (Follicle Stimulating Hormone) in both genders.

In females, FSH indeed acts on ovarian follicles. It stimulates the growth and maturation of these follicles, which is critical for oocyte development and estrogen production. Consequently, FSH plays a fundamental role in the menstrual cycle and fertility in females.

In males, however, FSH acts on the Sertoli cells, not the Leydig cells. The function of FSH in males is to promote spermatogenesis by acting on Sertoli cells in the testes, which support the development of sperm. On the other hand, Leydig cells, influenced by Luteinizing Hormone (LH), are responsible for the production of testosterone, a primary male sex hormone.

Moving on to Reason R, which asserts that "Growing ovarian follicles secrete estrogen in female while interstitial cells secrete androgen in male human being." Both parts of this statement are accurate. In females, the growing ovarian follicles indeed secrete estrogen, pivotal in regulating the female reproductive cycle and secondary sexual characteristics. In males, interstitial cells, another term for Leydig cells, produce androgens, like testosterone, vital for male reproductive functions and characteristics.

Given this, Assertion A is false because its statement about FSH acting on Leydig cells in males is incorrect. However, Reason R is true as it accurately describes hormone secretion by ovarian follicles and Leydig cells in females and males, respectively.

Therefore, the correct answer is:

Option D: A is false but R is true.