The correct option is D Placenta
The placenta is an organ, that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination etc. hCG is human chorionic gonadotropin hormone, that can be found in maternal blood and urine shortly after implantation has occured. hCG is present only during pregnancy as it is secreted by the placenta. The syncytical layer of chorionic villi of placenta secretes hCG.
Thus, the correct answer is option (D).