Answer is for the earths core to cool enough for convection to stop, then the plates would have no convection current to move them.
Explanation: If the Earth's core were to cool down, the convection currents in the mantle would stop moving. Since the convection currents drive the plates, they would stop moving.
The correct answer is vacuole. Vacuole controls the water input and water output of an amoeba. It is found within endoplasm. The vacuole is an essential part of an amoeba because it maintains the life of an amoeba. Malfunction can cause the amoeba to burst.