In controlled experiments: Group of answer choices
1. all variables are held constant.
2. one variable is manipulated, while others are held constant.
3. all critical variables are manipulated.
4. all variables are dependent on each other.
5. all variables are independent of each other.

The option 2) is correctThat is In controlled experiments " One variable is manipulated, while others are held constant "

Step-by-step explanation:

Given that  Controlled experiments.

To find the choice from the group of answer choices:  A controlled experiment is an experiment in which all variables are held constant except for one that is the independent variable." One variable is manipulated, while others are held constant " is correct answer.Therefore option 2) is correct