instruction:
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. 
question:
Bees land on flowers and eat the nectar of the plants. While on the flowers pollen gets on the bee's fur. The bee flies to another area with other flowers. The pollen is deposited in that area. A plant is able to reproduce. 
answer:
bee ,nectar ,pollen 


question:
Fuels burns in the combustion chamber. The burning fuel creates energy. The upward motion cause air to be released into the cylinder. The piston compresses the air. A spark ignites the fuel and air inside the cylinder. The pressure pushes the piston down. The exhaust valve opens. The piston pushes the air out of the cylinder. 
answer:
fuel ,air ,spark ,pressure 


question:
Batteries are put in a flashlight. The flashlight is turned on. Two contact strips touch one another. A circuit is completed between the batteries and the lamp. The lamp in the flashlight begins to glow. The reflector in the flashlight directs the lamp's beam. A straight beam of light is generated. The flashlight is turned off. The circuit is broken. The beam is no longer visible. 
answer:

batteries ,flashlight ,lamp ,straight beam of light ; beam ,circuit