The answer should be nucleus
The circulatory system transports the nutrients and oxygen throughout the body, and the excretory system will excrete the waste and the body will start to sweat in response to the heat to maintain homeostasis.
An abyssal plain is an underwater plain on the deep ocean floor, usually found at the depths between 3000 and 6000 m. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They are among the flattest, smoothest, and least explored regions on Earth.
