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QUESTION
Question :1 Which of these variables could be investigated ONLY through observational studies? A) all of the variables B) the brand of detergent used to remove a stain C) the presence or absence of sk
Question :1
Which of these variables could be investigated ONLY through observational studies? A) all of the variables B) the brand of detergent used to remove a stain C) the presence or absence of skin cancer in a human D) the presence or absence of a cooling device in a gadget
