Which of the following are true for gravity?

I do not know any of the answers so I would probably say; gravity is the force that holds objects on the surface of the earth.

Since there are no options given so we can simply define gravity and its constraints.

Gravity, also called gravitation, is a force that exists among all material objects in the universe. Gravity is an attractive force, so it pulls all objects together irrespective of their masses. But it is understood that the object with larger mass will attract the smaller one towards itself. And as the distance between two objects increases, the force of gravity between them decreases.

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.