Final answer:
The correct answer is 'b. Gestation is too late' because at 170 days of gestation, the fetus is well-developed and prostaglandin is unlikely to induce an abortion, being typically used earlier in pregnancy. The placenta has taken over the hormone production making the pregnancy less susceptible to hormonal changes.
Step-by-step explanation:
The question presented appears to be discussing the use of prostaglandin in inducing an abortion and why it might not be effective at 170 days of gestation. The option 'b. Gestation is too late' would be the correct answer here because at 170 days, which is well into the second trimester, the fetus is significantly developed. Hence, administering prostaglandin is not likely to induce an abortion as the medication is generally used to induce labor or for medical abortions in the earlier stages of pregnancy when the fetus is not as developed.
It is important to note that during early pregnancy, the corpus luteum produces essential hormones such as progesterone and estrogen that support the pregnancy. Should these hormone levels fall, it can lead to menstrual-like shedding of the uterine lining, which can disrupt an early pregnancy. However, by 170 days, the placenta has taken over hormone production, and the pregnancy is less susceptible to changes in hormonal levels induced by prostaglandin.