Which of the following is NOT one of the three reservoirs of the carbon cycle?

The correct answer identifies "rocks, plants, atmosphere" as not being one of the three primary reservoirs of the carbon cycle. The three main reservoirs of the carbon cycle are indeed the atmosphere, oceans, and geological carbon in rocks. These reservoirs play significant roles in storing and cycling carbon through various processes.

While plants are a crucial part of the carbon cycle as they act to absorb carbon dioxide during photosynthesis, they are not classified as a reservoir in the same sense as the larger, more stable reservoirs such as rocks and oceans. The atmosphere contains carbon in gaseous form, while rocks (including fossil fuels) store carbon over geological timescales.

This distinction is important because understanding the roles of the carbon reservoirs helps clarify how carbon is stored and cycled in the environment, as well as the implications for climate change and ecosystem dynamics.