Answer:
The answer is the second option: Dependent variable, experimental group and control group
Step-by-step explanation:
Let's list out all possible variables/groups in the option
Independent variable: This is a variable that is intentionally (directly or indirectly) altered by the one doing the experiment but is not affected by any variable/group during the course of the experiment. No Independent variable was mentioned.
Dependent variable: This is a variable that is affected by another variable and is usually the variable been tested during the course of an experiment. The dependent variable here is the effectiveness of a new nutrient supplement.
Experimental group: This is the group that is being treated during the course of an experiment. The experimental group here is the group of identical mice given the supplement.
Control group: This is a reference group that is not given any treatment during the course of an experiment. The control group here is the group of identical mice not given anything.
From the above description, it can be deduced that the parts of the experiment described in the scenario in the question is dependent variable, experimental group and control group.