Answer: b. hCG
Step-by-step explanation:
Human chorionic gonadotropin hormone (hCG) is the hormone which is only type of hormone produced during the period of gestation or pregnancy. It is exclusively produced inside the placenta. The levels of this hormone found in maternal blood as well as in the urine increase considerably during the first trimester. This can contribute to vomiting and nausea associated with tenure of pregnancy.