Which of the following drugs is NOT likely to cause pupil dilation?

Narcotic analgesics, which include drugs such as morphine, heroin, and oxycodone, are primarily known for their ability to cause pupil constriction, a condition known as miosis. The mechanism of action for these substances primarily involves the opioid receptors in the brain, which lead to several physiological responses, including the characteristic reduction in pupil size.

In contrast, cannabis, CNS stimulants, and hallucinogens are known to often induce pupil dilation (mydriasis) as part of their psychological and physiological effects. This distinction makes narcotic analgesics the most unlikely to cause pupil dilation among the options provided. Understanding this is crucial for drug recognition experts when differentiating between instances of substance use and the signs associated with specific drug categories.