Correct Response: B. Lichens, plant roots, and fungi can produce weak acids to break down rock. This is an important part of weathering that makes the minerals in rocks available for use by these organisms and others. Molecular water that exists in the crystal structure of some minerals is bound to the minerals and typically not available for biological activity (A). These organisms cannot extract minerals directly from rocks through osmosis because osmosis is the diffusion of water (C), and while salts can cause chemical weathering they are not produced by these organisms (D).
