The correct option is C Embryo develops normally till birth
By week 12, the placenta is formed and ready to take over nourishment for the baby.
Trophoblast refers to outer cells of a blastocyst that serve in placenta formation in the beginning of the second trimester. It secretes human chorionic gonadotropin that ensures persistence of the corpus luteum. The later serves to secrete ovarian hormone estrogen, progesterone, and relaxin that are required to maintain pregnancy. Hence, removal of ovaries after 4th month would not affect the pregnancy.
So if the ovaries of a pregnant woman are removed in the 4th month of pregnancy then the embryo develops normally till the birth. So option C is correct.