Answer:
The type of food Bob is given.
Explanation:
An independent variable in an experiment is the variable that is changed. Here, the type of food is the only thing that is changed and the amount of water, temperature and other variables were kept constant (same). Thus, the independent variable is the type of food Bob is given.
It’s magnesium magnesium has 3 levels and carbon only has two levels
Answer:
hepatitis A is the only one