Which among the following protein complexes enhances Follicle-stimulating hormone, biosynthesis and secretion, and participates in the regulation of the menstrual cycle?

Activin is a protein complex which enhances Follicle-stimulating hormone biosynthesis and secretion, and participates in the regulation of the menstrual cycle. Many other functions have been found to be exerted by activin, including roles in cell proliferation, differentiation, apoptosis, metabolism, homeostasis, immune response, wound repair and endocrine function.