The correct answer is option b, that is, circadian rhythms.
A roughly 24-hour cycle in the physiological procedures of living beings, comprising animals, plants, fungi, and cyanobacteria is known as a circadian rhythm. In a strict sense, circadian rhythms are produced endogenously, however, they can be modulated by external cues like temperature and sunlight.
The circadian rhythms can affect the release of the hormone, sleep-wake cycles, digestion and eating habits, the temperature of the body, and other essential functions of the body.