If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Biogeochemical cycles

Problem

The diagram below illustrates part of the carbon cycle.
At point X, carbon is most likely to be in which form?
Choose 1 answer: