Independent: Gasoline with different amounts of lead
Dependent: Amount of pollution produced
Answer:
represents oxidation.
Explanation:
Oxidation-reduction reaction or redox reaction is defined as the reaction in which oxidation and reduction reactions occur simultaneously.
Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.
Example:
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.
Example: 
represents oxidation.