Answer:
A Type of Drink
Explanation:
A controlled variable remains constant throughout the experiment.
In such experiment, you'd test the volume of one single caffeinated drink. You'd have to use the same type of drink every trial.
The key is a process called <span>pasteurization</span>
B) Seawater. Because, it all has the same consistency. With the other choices, like vegetable soup, in one spoon full you may get a bit of potato but in another spoon full you may get a lima bean.
