Which of the following is an activity related to the production of controlled substances?

Harvesting is an activity specifically related to the production of controlled substances because it involves the process of collecting the raw materials from plants or crops that can be used to create these substances. In controlled substance production, harvesting is a critical step that takes place after cultivation, where the plants are fully grown and ready to be processed into drugs.

The other activities listed do not directly relate to the production phase. Distribution of seeds pertains to the initial phase of cultivation rather than production. The sale of narcotics occurs after production and involves legal and illegal market transactions, while the consumption of drugs is the end-user step, indicating the final use of the produced substances. Thus, harvesting stands out as a direct link in the actual production process of controlled substances.