Where does the atmosphere of the earth end? (i. e. where is the top of the earth's atmosphere? ) where does the atmosphere of the earth end? (i. e. where is the top of the earth's atmosphere? )
a. the tops of thunderstorms are at the top of the earth's atmosphere.
b. there is no definite top to the atmosphere. the pressure and density gradually get smaller as the altitude gets larger.
c. the top of the earth's atmosphere is about 100 kilometers below the orbit of the international space station.
d. the earth's atmosphere ends at the point where the aurora (northern lights) begin.

b. There is no definite top to the atmosphere. The pressure and density gradually get smaller as the altitude gets larger.

Explanation:

There is no specific top of the atmosphere. It varies from place to place. But generally it is considered to be 480 kilometers thick.  But majority of its thickness is limited to 16 km only above earth surface. The pressure and density gradually get smaller as the altitude gets larger. The air pressure at sea level is 14.7 pounds per square inch and it decreases to 10 pounds per square inch at a height of 3 kilometers. From the above discussion we say that option B is correct

conservation of mass

mass before something happens = mass afterwards