Hakeem is testing the effects of sunlight on samples of soil.  which of these actions would introduce confounding variables into hakeem’s experiment? he tests a theory that’s already been established. he tests multiple hypotheses at a time. he uses identical specimens when completing multiple trials. he adjusts the independent variable and records the effects. he uses different types of soil in each of his samples.

He tests multiple hypotheses at the same time. This would introduce the possibility for a confounding variable to alter his results.

The correct answer is by testing multiple hypothesis at a time and by using different kinds of soil in each of the samples.

Explanation:

An external effect that changes the effect of an independent variable and the dependent variable is considered as a confounding variable. This extraneous effect has an application in influencing the result of experimental design. The confounding variables can hamper and can produce unnecessary results in an experiment.  

In the given case, by testing multiple hypotheses at a time and by using different kinds of soil in each of the samples the confounding variables can be presented.  

answer; i believe the correct answer to the above question is ( friction)

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]