Fact 1: Plastics are made from petroleum and produce toxic waste.

Fact 2: Crude petroleum is imported for refining.

Given the two facts above, answer the question "what does making plastic require?" with the following options: 
- digestion
 - weathering
 - less water
 - adding heat
 - recycling
 - Energy
 - death
 - refining


 

        refining 