joannachavez12345
joannachavez12345
04.11.2021 • 
Biology

What has happened to carbon dioxide levels in the atmosphere? Select one:

a.
They have been rising at least since 1958

b.
They rose in the 1950s and 1960s, but are now stable

c.
They have been declining since around 1972

d.
None of the options

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