Which of the following is NOT a common cooking equipment used in clandestine labs?

Microwave ovens are generally not considered common cooking equipment in clandestine labs primarily due to their specific functional design and limitations. Clandestine labs are often set up to manufacture illegal substances, and the processes involved typically require very precise temperature control and chemical reactions that may not be achievable through microwave technology.

In contrast, hot plates, crock pots, and coffee grinders are more aligned with the types of equipment that would be utilized in such environments. Hot plates allow for accurate heating and temperature control essential for many chemical reactions. Crock pots can provide slow cooking capabilities, which might be necessary for certain processes that require longer cook times at stable temperatures. Coffee grinders are often used to finely process substances, which is a common step in many illicit drug manufacturing procedures.

The absence of microwave ovens in this context can be attributed to the nature of the operations conducted within clandestine labs, where the risks of igniting volatile mixtures or causing explosive reactions are significant concerns that dictate the choice of cooking equipment.