(b) prolactin

Explanation:

Prolactin (also called leuteotrophic) hormone is associated with lactation (secretion of milk from the mammary gland). Therefore, to yield more milk cow is injected with prolactin hormone. Sorbitol is a sweetner found in some fruits (like apple, peers etc). Gonadotrophs a type of basophil in the adenohypohysis (anterior pituitary gland) whose granules secrete FSH (follicele-stimulating hormone) and LH (luteinizing hormone). Stilbesterol is synthetic estrogen used in hormone therapy, as a post-coital contraceptive, and as a growth-promoting agent for livestock.