"False labor" is a result of what type of contractions?

A. Surfactant reduces surface tension in the alveoli, aiding in lung expansion, but it does not directly stimulate breathing.

B. CO2 accumulating in the infant's blood: The accumulation of CO2 in the infant's blood is a significant stimulus for the first breath after birth. High levels of CO2 trigger the infant's respiratory centers to start breathing.

C. Prostaglandins are involved in labor and delivery but do not directly stimulate breathing in the newborn.

D. An increased O2 level in the infant's new environment: Increased O2 levels do not directly stimulate breathing; rather, the accumulation of CO2 is the primary stimulus.

A. The endometrium is the inner lining of the uterus that supports the embryo after implantation, but it does not provide direct fetal nutrition or secrete hormones for fetal development.

B. The placenta is the organ that provides fetal nutrition, gas exchange, and waste removal. It also secretes hormones such as human chorionic gonadotropin (hCG), progesterone, and estrogen, which are essential for maintaining pregnancy and supporting fetal development.

C. The blastocyst is the early stage of the embryo that implants into the endometrium, but it does not provide fetal nutrition or secrete pregnancy-regulating hormones.

D. The myometrium is the muscular layer of the uterus responsible for contractions during labor, but it does not provide fetal nutrition or secrete hormones.