Which is a main characteristic of delirium?

A main characteristic of delirium is confusion with fluctuating consciousness. Delirium is an acute, often reversible condition that involves a disturbance in attention and awareness, which can lead to confusion. Individuals experiencing delirium may have difficulty focusing, following conversations, or maintaining a coherent thought process.

The nature of delirium is such that symptoms can fluctuate throughout the day. For example, a person might be relatively clear-headed in the morning but become confused or disoriented in the evening. This fluctuation sets delirium apart from more chronic conditions, where cognitive decline is more stable and persists over a longer period, such as in dementia.

In summary, the hallmark of delirium is this confusion and impaired attention, characterized by a rapid onset and potential reversibility, making the option regarding confusion with fluctuating consciousness the correct choice.