_The middle zone of the earth with a thickness of 2780 km having an average density of 5.6 is known as:$?

_The middle zone of the earth with a thickness of 2780 km having an av

1.	_The middle zone of the earth with a thickness of 2780 km having an average density of 5.6 is known as:$?
A.	Rosphere
B.	Osophere
C.	Pyrosphere
D.	Cyrosphere
Answer» D. Cyrosphere