Of these four scientific designs, choose the one that has a biased design.
1.in a study to determine how bees react to color, both color and light levels are varied.
2.in a study of the effect of temperature on chick hatching times, all variables are controlled except temperature.
3.in a study of the effect of a vitamin on energy levels, the experimental and control groups each have 50 randomly chosen people.
4.in a study of the effect of an antibiotic on bacterial populations, there are several experimental groups at different antibiotic concentrations and one control group receiving no antibiotic.

The correct option is A.

Explanation:

In scientific investigations, there are usually two variables; independent and dependent variables. The value of independent variable is usually changed in order to test its effect on the dependent variables. This means that in a scientific investigation, only one variable should be changed per time in order to determine its effect on the other variable.

In the scenario given in option A, you will notice that the two variables in the investigation were changed at the same time. This is wrong and is an example of a biased design.

a

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.