Which cycle of activity has an approximate duration of 365 days and operates independently of environmental cues?

The choice indicating a cycle of activity with an approximate duration of 365 days that operates independently of environmental cues is accurate because it describes a circannual rhythm. These rhythms are biological cycles that affect physiological processes, life cycles, and behaviors across a yearly timeframe.

Circannual rhythms enable organisms to time critical events in their life cycles, such as breeding, migration, and hibernation, according to seasonal changes, but they can also function without direct environmental signals. This internal timing mechanism is regulated by endogenous biological clocks and is often entrained by seasonal variations, allowing organisms to prepare for climatic changes despite not relying solely on environmental cues.

In contrast, a circadian rhythm lasts about 24 hours and is influenced by environmental light and dark cycles, while a circatriginta rhythm refers to a 30-day cycle that is typically associated with lunar phases and is not as widely recognized as an independent biological clock. Circumastric rhythms relate to the movement of organisms around the globe, but they do not pertain to a yearly cycle. Therefore, the characteristic of the circannual rhythm, operating independently yet aligned with the annual cycle, is what makes it the correct answer.