To produce some sounds, the flow of air out of the lungs is interrupted by the lips; for other sounds, the flow is disrupted by the placement of the tongue and teeth. This feature of sound production is referred to as

a. place of articulation.
b. manner of production.
c. voicing.
d. speech locus.

a. place of articulation.

Explanation:

The place of articulation are the location in the body where the there is a friction or blockage to the free flow of air usually in the larynx, mouth or lips. On the other hand, the manner of articulation is simply the way these articulators are placed to make effective speech possible without friction or blockages.

These places of articulation simply put are contact points where friction occurs between active articulators like the tongue and other articulators that are not directly involved like the mouth. This is necessary for effective sound production to take place. Production of consonant sounds is more common.

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.