It is january and haley, sarah and becky are tired of having cold feet while waiting for the school bus to come in the morning. they decide to design an experiment to test the effectiveness of wool, cotton and nylon as insulators. they fill identical bottles with 200 ml of water at 100 c and place inside each sock. they take the temperature of the water after 20 minutes.

what is the independent variable (manipulated variable) in the following experiment?
question 2 options:

identical bottles with 200 ml of water.

the different types of sock materials as insulators.

the temperature after 20 minutes.

having cold feet.