Answer:
the answer to this question is choice D
The presence of a controlled substance must be proven in both the blood and the organs before it can be considered as a cause of death.
A controlled substance is the one that is prohibited or available under strict regulations by the law of a country or state. These are usually the drugs that can result in addiction or serious diseases in an individual. Such substances are only available for medicinal purposes.
Blood is a red colored fluid present inside the body. It is red due to the presence of a pigment called hemoglobin. The blood is responsible for the transport of substances across the whole body, like oxygen, hormones, carbon dioxide, waste material, etc.
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The correct answer to your question is <span>D. mushroom
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Because if we're simultaneously moving/manipulating two different variables it can be very hard to determine why one variable is changing and why the other is changing. While this can be done with more complicated experimental designs, it usually is the case that scientists will only manipulate one variable and not two different ones.