Question

question 2 (10 points)
which of the following statements about a controlled experiment is true?

a scientists never use controlled experiments
b controlled experiments cannot be performed on living things
c only one variable is tested at a time
d all the variables must be kept the same

Explanation:

• Option a: Scientists often use controlled experiments to test hypotheses, so this is false.
• Option b: Controlled experiments can be performed on living things (e.g., in biology experiments with organisms), so this is false.
• Option c: In a controlled experiment, only one independent variable is tested at a time while other variables are controlled (kept constant), which is the correct characteristic of a controlled experiment.
• Option d: In a controlled experiment, only the independent variable is manipulated, and other variables are kept the same (controlled), not all variables (since the independent variable is changed), so this is false.

Answer:

c. Only one variable is tested at a time