A measuring cylinder contains water. A small metal block is lowered slowly into the water and then taken out. Next, a piece of plastic is fixed to the metal block, and the block is once more lowered slowly into the water. The diagrams show the measuring cylinder at each stage of this process. What is the volume of the plastic piece?
- A$10\,\text{cm}^3$
- B$25\,\text{cm}^3$
- C$70\,\text{cm}^3$
- D$80\,\text{cm}^3$