The answer is: In solution, rocks are C. dissolved by salts and acids.
Solution is homogeneous mixture composed of two or more substances (in this example differente rocks).
Homogeneous mixture has the same proporties of its components throughout any given sample.
If the rock is only smashed, it will form heterogeneous mixture.
Rock has solid shape because strong ionic bonds (intramolecular forces).
Acid can dissolve rock, water usually not.