Yes it is C but for future reference, both A and B are referring to solids, and D is referring to a gas, hope this is helpful later!
Answer:
A mass movement can either be slow or rapid. The slow downward movement of materials in a slope is called creep. This happens when the soil loosens up because of water and burrowing animals. In contrast to this, the rapid movement of large materials in a slope is called landslide.
If the Na+ voltage-gated channels in a muscle cell open, the Na (sodium) ions rush inside the muscle cell and makes the cell more positive as Na ions carry positive charge on it. Due to the entry of positively charged ions inside the cell, the cell becomes less negative and more positive. This is called depolarization of cell.
