The correct answer is the option: c. do not involve manipulation of an independent variable.
Descriptive research methods do not involve the manipulation of an independent variable. This is because descriptive research is designed to simply describe the characteristics of a phenomenon, rather than to explain or understand it.
Descriptive research is an important tool for understanding a phenomenon. By simply describing the characteristics of something, we can learn a great deal about it. However, we cannot use descriptive research to explain or understand a phenomenon. This is because we cannot manipulate an independent variable in descriptive research. We can only observe and describe what is already there.
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