A radiograph of an AP projection of the ankle reveals that the lateral surface of the ankle joint is totally open. (It should not be open on a true AP projection.) The technologist is positive that the ankle was in the correct, true AP position with the long axis of the foot perpendicular to the IR. What else could have led to this joint space being open?

Arthritis, Ankle dislocation

Explanation: Arthritis presents with widening of joint space due to degeneration of articular surfaces, also dislocation can presents as joint space widening

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.