Which of the Following Is a True Statement About Carbon

Multiple Choice

Which of the following is a true statement about carbon and the carbon cycle?

A) There is a one-way flow of carbon from volcanoes to plants to herbivores to carnivores and, finally, to the atmosphere.
B) Carbon is recycled among plants, animals, water, soil, and the atmosphere.
C) Carbon dioxide (CO₂) is the only carbon-containing compound involved in the carbon cycle.
D) Carbon is recycled in a general sense, but once carbon dioxide is exhaled from animals, it can only enter the atmosphere, where it's trapped and adds to the greenhouse effect.