[单选题]
The graph shows the level of hormones
mqd9r j,fw9c3in a woman's body during pregnancy
h, k l st5.hr48jgmxq40vz4ks. Which line on the graph represents the level of hum
0k4s,qk4tlv8.h4 5r mshjg x zan chorionic gonadotropin?
A.
B.
C.
D.
参考答案:
D
本题详细解析:
During pregnancy, the levels of human chorionic gonadotropin (hCG) increase to maintain the corpus luteum in the ovary, so that estrogen and progesterone are secreted to maintain the uterus lining and prevent ovulation. Once the placenta takes over the support of the embryo, hCG levels fall. Choice D is correct.
Choice A is incorrect as it represents estrogen which rises towards the end of pregnancy to promote contractions. Choice B is incorrect as it represents progesterone which decreases towards the end of pregnancy to promote contractions. Choice C is incorrect, as the hormones involved in pregnancy all fluctuate and do not remain stable.
