Which of these best describes Earth's mantle?
Most dense layer, consists of the outer and inner parts
Thinnest under the oceans and thickest under continents
Middle layer, density increases with depth as pressure increases
Least dense layer overall, consists of two layers of different thickness

The best description of Earth's mantle is it is made up of rock so hot that it flows. This layer is also called the asthenosphere. This Earth's mantle has a thickness that reaches 2,900 kilometers to wrap up the Earth's core. It is a rocky layer that covers 84% of Earth's volume.

Explanation:

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."