Question

In a controlled experiment, ________.
A. the researcher knows the outcome before beginning the experiment
B. you need only a single experimental organism which is tested again and again
C. the researcher has several hypotheses, one of which will be proven correct
D. the researcher controls for the effects of all variables except one
E. the researcher controls for the effects of only one variable

Answer 1

Answer:

D. the researcher controls for the effects of all variables except one.

Explanation:

Controlled experiment refers to an empirical test that is manipulated directly by a scientist to test a single variable at one point in time. The testing variable is the independent variable which is manipulated to see the effects on the system under observation. To minimize the effects of controlled variable on the subject, the controlled variables are controlled accordingly.