According to the content, what is NOT a method of concealment for narcotics?

Carrying narcotics in a backpack is typically not considered a method of concealment in the same way that the other options are. The use of items like furniture, underbody compartments of vehicles, or glove boxes usually denotes a more strategic effort to hide the substances from detection. These methods often involve significant alterations to spaces or the use of separate compartments designed to obscure the contents.

In contrast, placing narcotics in a backpack is a common and relatively visible method of transport. Backpacks can be easily searched and accessed, making this method less effective for concealment. Therefore, while using a backpack might be a way to carry narcotics, it does not provide the same level of concealment as the other methods listed, which are more specifically aimed at avoiding detection by authorities.