1. Testing only one variable
A controlled variable means its the one that stays the same. In a controlled experiment, it means there is only one manipulated, (changed) variable.
In my opinion, the correct answer among the choices listed is option C. The members of the kingdom Protista are least similar to a bacteria. Protists are eukaryotic organisms which cannot be classified as a fungus, animal, or a plant. They are mostly unicellular organisms.
Mutations are disruptions in the human body
The majority of the accessible drinking water on our planet comes from glaciers.
