Final answer:
Levels of blood components that fluctuate according to circadian cycles do so on a daily basis, as circadian rhythms denote biological processes that repeat every 24 hours, influenced by environmental light cycles.
Step-by-step explanation:
If levels of blood components fluctuate according to the circadian cycle, it means that these fluctuations occur daily. A circadian rhythm is a natural, internal process that regulates the sleep-wake cycle and repeats roughly every 24 hours. It is not only linked to our sleep patterns but also affects our body temperature, heart rate, blood pressure, and blood sugar levels. Therefore, the correct answer to the question is 1) daily.
Circadian rhythms are associated with the Earth's 24-hour rotational period and are common across multiple species, including humans. These biological rhythms are controlled by a biological clock located in the brain, which sends signals to the body and adapts to environmental light cues, prompting regular changes in various body processes.