In an unchanging environment (such as a cave) , people become sleepy about once every __________ hours.

A) 12-13
B) 24-25
C) 28-29
D) 48-49

Sleepy

A state of tiredness or drowsiness where an individual feels the need for sleep, often due to lack of rest, exertion, or specific sleep disorders.

Cave

A natural underground space large enough for a human to enter, often formed by the weathering of rock and leaving behind a void.

Hour Intervals

Fixed periods of time, each lasting exactly sixty minutes, often used as a measure for scheduling or tracking events.