A gas bubble is created far below the water surface. Its volume is $40\,\text{cm}^3$ and the pressure inside it is $P$. As the bubble moves upwards through the water, its volume grows to $56\,\text{cm}^3$ and the pressure changes to $100\,\text{kPa}$. The gas temperature remains constant. What is the starting pressure $P$?
- A$71\,\text{Pa}$
- B$71\,\text{kPa}$
- C$140\,\text{Pa}$
- D$140\,\text{kPa}$