Which of the following is a common indicator of methamphetamine labs?

The presence of containers with tubes or hoses attached is a common indicator of methamphetamine labs due to the specific processes involved in the illegal manufacture of meth. These labs typically use various chemical reactions that require specialized equipment for the manipulation of gases and chemicals, which often involves tubing and hoses to transfer substances between containers.

The configuration of these containers is crucial in facilitating the various steps in meth production, including heating, combining, and cooling chemical mixtures. The hazardous nature of the chemicals involved means that the setup often resembles a laboratory environment, complete with makeshift apparatus for filtering and distilling. Law enforcement officers are trained to recognize these setups as significant warnings of illegal drug activity.

In contrast, the other options, such as tools used in carpentry, medical equipment, and organic farming supplies, do not have specific associations with the production of methamphetamine and may be found in a variety of legitimate contexts that do not indicate drug manufacturing activities.