What is an example of a method for human consumption of substances?

The correct answer is injection because it is a direct method used for administering substances into the body, often involving the intravenous or intramuscular route. This method allows for rapid absorption and can be used for various formulations, including medications, vaccines, and other substances intended for human use. Injection is a common practice in medical settings and for certain types of drug delivery, highlighting its significance in the context of how substances are consumed by humans.

In contrast, packing, cultivation, and separation are not direct methods of human consumption. Packing generally refers to the process of wrapping or containing goods for storage or transport. Cultivation is the act of growing plants or crops, which is more about the production of substances rather than their direct consumption. Separation is a process used to divide mixtures into their constituent parts and does not relate to methods of consumption. Thus, injection stands out as the most appropriate choice for a method of human consumption.