A rock can be broken down into different kinds of substances by physical processes. No chemical reactions are needed to separate different parts of a rock into pure substances. This is because a rock is a
A. compound
B. element
C. mineral
D. mixture

2. what two items do autotrophs take from the environment to produce their food? 3. what are the two items that are released during transpiration from leaves? 4. what are the two membranes of the system? a.what are the two stages of photosynthesis? what are the two parts of photosynthesis?