In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
One example is below.
Q:  Magma rises from deep in the earth. The magma goes into volcanos. The volcanos pressure the magma upwards. The pressure causes the magma to push through the surface of the volcano. The lava cools. The lava forms new rock. New magma is pressured to the surface of the volcano. The volcano bursts through the rock the formed after the last eruption. 
A:  magma ,lava ,new rock 
Rationale: The entities are present in the process paragraph and they undergo state change. So, this is a positive example.
Q: You breathe in through your nose or mouth. The air travels through your windpipe. Into your lungs. Inside your lungs are tiny air sacs. The air sacs transfer the oxygen into your blood. The oxygen travels through your blood stream. The carbon dioxide from your blood stream is transferred to your air sacs. You breathe out and expel the carbon dioxide from your lungs. 
A:
air ,oxygen ,carbon dioxide 