1. Complete the sentence. Carbon flows between , environmental storage centers that absorb and store carbon for long periods of time. plants and animals humans and air rocks and soil carbon sinks

2. Arctic sea ice melts back during summer and grows or "recovers" during winter. The winter maximum extent is usually reached in March. The graph below shows Arctic sea ice extent every September since 1984.

Graph shows Arctic ice extent every September since 1984, which was approximately seven million square kilometers. In 1992, the Arctic ice extent was still averaging seven million square kilometers. By 2000, the Arctic ice extent was six million square kilometers. By 2008, the Arctic ice extent was four and a half million square kilometers. By 2016, the Arctic ice extent was four and a half million square kilometers after a dip to three and half million square kilometers in 2012.
© 2021 NSIDC/NASA

Which statement best describes how evidence of Arctic ice melt changed over time?

The Arctic ice has decreased three million square kilometers in 32 years.
Arctic ice extent in the year 2016 is equal to Arctic ice extent in 1984.
Arctic ice extent is lowest in September 2016 and highest in 1984.
The Arctic ice extent was highest between 2000 and 2016.