Question

Passage A
The nearly universal presence of sleep across diverse animal species, despite the profound evolutionary risks of rendering an organism vulnerable to predation and preventing foraging for extended periods, strongly suggests it serves a physiological function of paramount biological importance. Recent neurological research heavily favors the metabolic clearance hypothesis. During waking hours, the intense metabolic activity required by the brain's neurons results in the inevitable accumulation of neurotoxic waste products, such as beta-amyloid, in the interstitial space between cells. Sleep appears to be the specific state during which the brain's glymphatic system becomes highly active, expanding interstitial volume and effectively flushing these toxic byproducts into the circulatory system for disposal. In this view, sleep is fundamentally a restorative maintenance period, necessitated by the steep biochemical cost of conscious neural activity. While cognitive benefits and improved alertness undeniably follow a period of sleep, these should properly be understood as secondary evolutionary dividends rather than the primary adaptive driver of the behavior. If a complex biological system runs intensely, it requires a dedicated period of systemic downtime for essential cellular housekeeping; sleep is the behavioral manifestation of this unavoidable physiological requirement.

Passage B
Historically, traditional theories of sleep have tended to cast it as a largely passive state of systemic recovery, conceptually akin to a complex machine being temporarily powered down to prevent overheating and mechanical wear. However, this strictly metabolic-centric view is increasingly giving way to a more sophisticated understanding of sleep as a highly active neurological state that is absolutely crucial for information processing and cognitive function. The synaptic homeostasis hypothesis proposes that waking life is characterized by a net increase in synaptic strength across the cerebral cortex due to continuous environmental interaction and learning. This relentless strengthening process is metabolically unsustainable and quickly leads to cellular stress and spatial saturation, eventually making further learning and adaptation impossible. Sleep is the active, dynamic period during which the brain selectively downscales these synapses, consolidating crucial memories while aggressively pruning irrelevant informational noise. This active neural reorganization is exactly what prepares the brain for new acquisitions the following day. While it is true that the brain also engages in metabolic clearance during this time—removing accumulated waste products of waking metabolism—this should be viewed merely as a concurrent background maintenance process. The true evolutionary imperative driving the persistence of sleep is cognitive optimization. Without this active nightly recalibration, complex nervous systems would rapidly become overwhelmed by the immense informational load of consciousness.

Based on the dual passages provided, which of the following statements about sleep would BOTH authors most likely agree with? Select all that apply.