Answer:
The answer is B.
Step-by-step explanation:
In an experiment, Shara feeds her rat different brands of rat food (brands X, Y, and Z) each for 2 weeks and weighs the rat over several days during the period of each diet.
What is the independent variable?
the rat's change in weight during the period
>the brand of food that Shara feeds the rat
the amount of water that the rat gets in each period
the duration of each period