The greeks had a theory based on the following thought process: an object is divided in half. its halves are divided again and again until the pieces cannot be divided any more. the smallest unit possible is called a(n)

relative humidity is a measure of the amount of moisture in the air relative to the total amount of moisture the air can hold.

so d

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).