[Solved] The names of the seven days of the week are based on A)the names of the seven planets closest to the Sun. B)the seven most prominent constellations in the summer sky. C)the names of prophets in the Bible. D)the seven naked-eye objects that appear to move among the constellations. Endorphins: Natural, pain-relieving chemicals produced by the body that promote a sense of well-being and can reduce pain. Neurotransmitters: Chemical substances in the nervous system that transmit signals from one neuron to another across synapses. Opioid Peptides: Natural chemicals in the brain that act like morphine, playing key roles in pain relief, reward, and addictive behaviors. Oxytocin: A hormone and neurotransmitter involved in childbirth, lactation, and social bonding.