Consider the below figure showing carbon dioxide level changes with time. 
What is the reason for the rise in CO2 levels?
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A set of access control technologies used by publishers or copyright holders to protect their intellectual property from unauthorized distribution or copying.
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A legal contract between the licensor and purchaser, establishing the purchaser's right to use the software.
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The act of acquiring goods or services in exchange for money.
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The act of recording or enlisting information, events, or transactions, often for official keeping or as a preliminary step to gain access to a service or system.
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