What is a defining effect of PCP use?

The defining effect of PCP (phencyclidine) use is visual and auditory hallucinations. PCP is a dissociative anesthetic that alters perceptions of reality and can lead to significant changes in sensory experiences. Users may experience vivid visual hallucinations, such as seeing things that are not there, as well as auditory hallucinations in which they may hear sounds or voices that others do not perceive. This alteration in sensory perception is a key characteristic of the drug, making option B the most accurate answer regarding PCP's effects.

Other effects, such as memory loss and emotional instability, can occur with various substances but are not as defining or commonly associated with PCP as hallucinations are. Additionally, while professional work impairment can result from the effects of PCP, it is not a specific or defining characteristic of its use in the same way that hallucinations are, as PCP's most distinctive feature is its acute impact on perception and cognition.