Question

an inert substance that resembles the treatment given to an experimental group is
a placebo.
an independent variable.
a variable.
a hypothesis.
never used in an experiment.

Explanation:

An inert substance matching an experimental treatment is defined as a placebo. Independent variables are the manipulated factors in experiments, variables are measurable quantities, hypotheses are testable claims, and this substance is intentionally used in experiments (like control groups), so the other options are incorrect.

Answer:

a placebo.