Final answer:
The progestin from the options provided is d) Norethindrone (Aygestin), which is a synthetic hormone used in birth control to mimic the effects of progesterone and prevent ovulation.
Step-by-step explanation:
The example of a progestin from the choices provided is d) Norethindrone (Aygestin). Progestins are synthetic forms of progesterone, which is a natural hormone involved in the menstrual cycle and pregnancy. Synthetic progestins, like norethindrone, are used in birth control formulations to prevent ovulation by mimicking the hormonal effects that occur naturally during pregnancy. For instance, birth control pills often contain a combination of synthetic estrogens and progestins to effectively prevent pregnancy. While other options like estradiol and raloxifene are types of estrogens, and bicalutamide is an anti-androgen, only norethindrone is a progestin.