Which best describes the mixed level of activity in delirium?

The mixed level of activity in delirium is characterized by periods of both normal and abnormal activity levels, often leading to fluctuating attention and awareness. This means that during the course of delirium, an individual may alternate between moments of alertness and periods of confusion or reduced cognitive function.

Option B accurately reflects this phenomenon, as those experiencing delirium can demonstrate periods of normal activity interspersed with episodes where their attention may wane or become less focused. This variability in attention and alertness is a hallmark of delirium, emphasizing the disorder's instability and the often acute nature of the symptoms.

Other options do not capture the fluctuating nature of delirium as effectively. For instance, low psychomotor activity with little alertness does not convey the mixed activity level that delirium presents, which often includes bursts of energy or normal behavior that suddenly shift to confusion. High energy levels with cognitive impairment might suggest a single direction of activity rather than the mixed state observed in delirium. Lastly, stagnant cognitive function with variable activity implies a more consistent cognitive status, which does not align with the fluctuating awareness and attention typical in delirium.