Answer:
mantle
Explanation:
A mantle is a layer inside a planetary body bounded below by a core and above by a crust. Mantles are made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density. All terrestrial planets (including Earth), a number of asteroids, and some planetary moons have mantles.
The environment includes abiotic (nonliving) and biotic (living) factors. An ecosystem consists of all the biotic and abiotic factors in an area and their interactions
the three general classifications are sensory neurons, motor neurons and interneurons. I don't know how they work together to produce a response to an environmental stimulus:( sorry