Why do biofilms form? don't tell me how it forms. i just want to know why it forms.

The biofilm can present one of the most important species of microorganisms, depending on the duration and its location. Gram-positive, Gram-negative and yeast. In addition, the cellular elements may be attached to the biofilm, such as platelets, for example, when the biofilm is installed on the blood-soaked surface.Several factors contribute to the formation of biofilms. The biofilm can present one of the most important species of microorganisms, depending on the duration and its location. Gram-positive, Gram-negative and yeast. In addition, the cellular elements may be attached to the biofilm, such as platelets, for example, when the biofilm is installed on the blood-soaked surface.Several factors contribute to the formation of biofilms, depends primarily on the number and type of cells present in the liquid to which the surface is exposed and the rate of flow of this liquid across the surface. The physical chemical properties of the surface, the nutritional composition and ambient temperature will also interfere with this speed. The presence of antimicrobials in the medium may affect the formation of biofilms.

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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.

they dont have any evidence