Rainforests produce most of the Earth's oxygen.

False! Most of the oxygen in our atmosphere, an estimated 50-80%, is actually produced by phytoplankton – microscopic algae and bacteria that live in the oceans. While rainforests contribute significantly to photosynthesis, they also consume a considerable amount of oxygen through the plants' own respiration and the decomposition of organic matter. Therefore, rainforests' net contribution of oxygen to the atmosphere is lower than many believe.