What characterizes nocturnal animals?

Nocturnal animals are characterized by being generally more active at night. This behavioral adaptation allows them to take advantage of the cooler temperatures and reduced competition from diurnal (day-active) species. Being active at night also aids in avoiding predators and increases their chances of hunting and foraging for food when their prey is more vulnerable or when there is less competition for resources.

The other options do not accurately reflect the characteristics of nocturnal animals. For instance, stating that they are primarily active during the day contradicts the definition of being nocturnal. Similarly, having a strict diet of plants only misrepresents the dietary habits of many nocturnal species, as some are omnivorous or carnivorous. Lastly, saying they sleep through the entire night does not align with their behavioral patterns, since their primary activity occurs during nighttime hours.