Question

many animals, including humans, must sleep, and sleep is known to have a role in everything from healing injuries to encoding information in long - term memory. but some scientists claim that, from an evolutionary standpoint, deep sleep for hours at a time leaves an animal so vulnerable that the known benefits of sleeping seem insufficient to explain why it became so widespread in the animal kingdom. these scientists therefore imply that
which choice most logically completes the text?
prolonged deep sleep is likely advantageous in ways that have yet to be discovered.
it is more important to understand how widespread prolonged deep sleep is than to understand its function.
most traits perform functions that are hard to understand from an evolutionary standpoint.
many traits that provide significant benefits for an animal also likely pose risks to that animal.

Explanation:

El texto dice que el sueño profundo deja a los animales vulnerables y que los beneficios conocidos no son suficientes para explicar su propagación. Entonces, debe haber beneficios no descubiertos. La primera opción (prolonged deep sleep is likely advantageous in ways that have yet to be discovered) es lógica. Las otras opciones no se ajustan: la segunda (it is more important to understand how widespread prolonged deep sleep is than to understand its function) no resuelve la paradoja; la tercera (most traits perform functions that are hard to understand from an evolutionary standpoint) es demasiado general; la cuarta (many traits that provide significant benefits for an animal also likely pose risks to that animal) no explica la propagación.

Answer:

A. prolonged deep sleep is likely advantageous in ways that have yet to be discovered.