Which of the following would constitute theft of a controlled substance?

Taking prescription medication without permission constitutes theft of a controlled substance because prescription medications are regulated by law and considered controlled substances. When an individual takes these medications without authorization, they are unlawfully taking property that belongs to someone else, typically a healthcare provider or pharmacy. This act not only violates the trust associated with the legal prescription process but also poses significant health risks, both to the individual taking the medication and to public safety due to potential misuse or abuse.

The other options do not involve controlled substances or theft as defined in this context. Removing waste products from a facility typically relates to disposal rather than theft, taking clothing does not involve controlled substances, and receiving stolen property pertains to the handling of stolen goods rather than the specific act of theft involving controlled substances.