TASK DEFINITION: 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. 
PROBLEM: The gravity of the sun pulls its mass inward. There is a lot of pressure on the Sun. The pressure forces atoms of hydrogen to fuse together in nuclear reactions. The energy from the reactions gives off different kinds of light. The light travels to the Earth. 

SOLUTION: atoms of hydrogen ,sunlight; light 

PROBLEM: A mold spore floats through the air. The spore lands on a piece of bread. The spore grows hyphae into the bread. The mold forms a colony. Sporangiophores grow upward. The mold sends out spores. 

SOLUTION: mold spore ; spore ; mold ,colony ; sporangiophores 

PROBLEM: Air contains invisible moisture called water vapor. Excess water vapor is condensed out as water in the form of water droplets. Water droplets are carried up into the clouds. The clouds become heavy with water droplets. When the cloud is saturated. Rain will fall. 

SOLUTION:
water vapor ,water droplets ,cloud ,rain