Final answer:
The statement that the suprachiasmatic nucleus regulates several circadian rhythms is true. The SCN is critical for aligning the body's internal biological clock with the external world.
Step-by-step explanation:
The suprachiasmatic nucleus (SCN) is true in its regulation of several circadian rhythms. The SCN, located in the hypothalamus, is often referred to as the brain's clock mechanism. It relies on light information received through projections from the retina to synchronize the body's internal clock with the external environment. This internal clock influences various biological processes, including sleep-wake cycles and hormone release, which follow a roughly 24-hour cycle aligned with the Earth's rotation.