What are two different ways a plant could control turgor pressure, a name for internal water potential within its cells? is this a sufficient definition for turgor pressure?

Turgor pressure is defined as the pressure exerted by the fluid in the cell, which presses cell membrane against the cell wall. The turgor pressure in plants is generated through osmotic inflow of water into cells.  

The plants control turgor pressure in two ways:

1. The plants actively transport the proteins to inside and outside of the cells to maintain the pressure exerted by the fluids.  

2. The cells increase or decrease the solute concentration inside the cells. The leaves perform evaporation changing the water concentration levels in the plant.

Therefore, the turgor pressure is pressure exerted by plasma membrane over cell wall. It can be explained as the cytoplasmic membrane's pressure over the cell wall that impact water potential.  

To know more about turgor pressure, refer to the following link:

link

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.