A controlled experiment___. A. Includes one group for which the scientist controls all variables. B. Includes at least two groups, one of which does not receive the experimental treatment. C. Includes at least two groups, one differing from the other by two or more variables. D. Is repeated many times to ensure that the results are accurate.

The correct answer is:

Includes at least two groups, one of which does not receive the experimental treatment. (B)

Explanation:

A controlled experiment is made up of at least two groups of participants (subjects). One group (the test group) receives the experimental treatment, which can be an intervention or a new drug to be tested etc, and the effect of the treatment on the subjects is measured, while the second group of similar subjects also known as the control group acts as a baseline and do not receive the treatment or intervention. They act as a baseline to ensure that the change observed in the treatment group was brought about as a result of the treatment.

Note that repeating the experiment several times does not ensure accuracy of the result, rather it ensures reliability of the results hence option D is not correct

ans.

gregor john mendel is known for study of inheritance in pea plants. he used garden pea plant for his study, having alternative traits for various characters. he performed cross-breeding in pea plants to check how characters are transmitted between parents to offspring, such as cross between pure tall and pure dwarf plant. mendel studied the inheritance patterns in pea plants for various generations.

thus, the correct answer includes options and f).