A Student Poses the Question: How Does the Presence of Dissolved

A student poses the question: How does the presence of dissolved salt affect the freezing point of water? To answer this question, the student set up two conditions. In the first condition, the student added salt to water in a container and referred to this condition as the variable. In the second condition, the student did not add any salt to water in a second container and referred to this condition as the control. The student took both containers and attempted to freeze the water at various temperatures to assess the freezing point. Would this be a valid experiment?

A) Yes, because there is more than one variable.
B) No, because there is not more than one variable
C) Yes, because there is one variable and a control
D) No because there is only one variable and a control