1.what is polarity, and why is water polar?

Polarity is when a molecule has a little bit of a charge on one side that's different from a charge on the other side so think of a north pole and a south pole when thinking of polarity.

So polarity is going to be a molecule that has different charges on the molecule so the bigger the difference in charge, the more polar. To make the definition easier, you can say that polarity is a difference in charge across a molecule.

Water is polar because it has a little bit of a negative charge on one end and a little bit of a positive charge on the other end so that's why water would be considered polar.

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.