The student wants to test the conductivity of each solution. Prior to carrying out the investigation, the student needs to identify the variables being controlled and the variables being changed between the two solutions. Which identification of the variables is correct?

Options:

The volume of the solution and the concentration of the solution are being changed between the two solutions, but the number of solute particles is being held constant.


The number of solute particles and the concentration of the solution are being changed between the two solutions, but the volume is being held constant.


The number of solute particles is being changed between the two solutions, but the volume and concentration of the solution is being held constant.


The volume of the solution and the number of solute particles are being changed between the two solutions, but the concentration of the solution is being held constant.