Ash trees are being removed when they show signs of the ash borer, a parasite that affects the trees and kills them off. what best explains why the ash trees are being cut down? the ash borer is a density-independent limiting factor, and humans need to clear cut to control tree density. the ash borer is a density-dependent limiting factor and will start to spread to nearby healthy trees. ash trees are outcompeting other trees and are thus more affected by the ash borer. long periods of drought have caused an increase in the ash borer population.

ANSWER:  Ash trees are being cut down because the ash borer is a density-dependent factor and will start spreading to nearby healthy trees.

REASONING:  Density-dependent factors are factors that effect the size or growth of the population.  These factors can vary with the population density.  The population of ash borers is density-dependent because if they are provided more habitat (ash trees), their population will increase.

B. The ash borer is a density-dependent limiting factor and will start to spread to nearby healthy trees.

Explanation:

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.

genetic variation will increase because of a new habitat and food source.

explanation: