Question

the only variables in the lab procedure are the independent variable, and the dependent variable,

Explanation:

In a typical lab procedure (especially in scientific experiments, which falls under Natural Science, specifically subfields like Biology, Chemistry, Physics, etc.), the key variables are the independent variable (the one manipulated by the experimenter), the dependent variable (the one that responds to the change in the independent variable), and often the controlled variable (the one kept constant to ensure a fair test). Wait, but the question here seems to have a dropdown for the first blank after "independent variable"—maybe a typo or misstatement? Wait, perhaps the first blank is supposed to be "controlled variable" (or "constant variable")? Wait, no—maybe the original question had a mistake. Wait, in experimental design, the main variables are independent (what you change), dependent (what you measure), and controlled (what you keep the same). But the way the question is phrased: "The only variables in the lab procedure are the independent variable, [blank] and the dependent variable, [blank]". That doesn't make sense. Wait, maybe the first blank is a label for the independent variable (like "the one you change") and the second for the dependent variable (like "the one you measure"). Let's assume standard experimental variables:

Independent variable: the variable that is manipulated or changed by the experimenter (e.g., amount of fertilizer in a plant growth experiment).

Dependent variable: the variable that is observed or measured to see the effect of the independent variable (e.g., height of the plant).

Controlled variables: variables kept constant (e.g., amount of water, light, soil type) but the question says "only variables"—maybe the question has an error, but if we go with standard, the first blank (after "independent variable") might be a description: "the one you change" and the second "the one you measure". But since it's a dropdown, maybe the options are like "controlled variable" (no, controlled is separate) or maybe the question is miswritten. Wait, perhaps the first blank is a mistake, and it's supposed to be "controlled variable" as the third variable, but the question says "only variables"—maybe the question is simplified. Alternatively, maybe the first blank is a label for the independent variable (e.g., "manipulated variable") and the second for dependent (e.g., "responding variable").

Assuming the standard definitions:

Independent variable: the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable.

Dependent variable: the variable being tested and measured in a scientific experiment, and it is 'dependent' on the independent variable.

So if the dropdown options for the first blank (after "independent variable") are something like "the variable you change" and the second (after "dependent variable") are "the variable you measure", then those would be the answers.

Answer:

First blank (after "independent variable"): the variable you change (or similar description of independent variable's role)
Second blank (after "dependent variable"): the variable you measure (or similar description of dependent variable's role)

(Note: Since the exact dropdown options aren't provided, this is based on standard experimental variable definitions. If the dropdowns have options like "controlled variable", that would be incorrect, but likely the options are descriptions of independent and dependent variables.)