An example of a biological rhythm is

• A. a state of increased alertness.
• B. hunger.
• C. the beat of the heart.
• D. dreaming.

Answer: (C)

Verified step by step guidance

1. Understand the concept of biological rhythms: Biological rhythms are natural cycles of change in our body's chemicals or functions. They are driven by internal biological clocks.
2. Identify different types of biological rhythms: These include circadian rhythms (24-hour cycles like the sleep-wake cycle), ultradian rhythms (shorter than a day, like the stages of sleep), and infradian rhythms (longer than a day, like the menstrual cycle).
3. Consider the options given: Increased alertness, hunger, the beat of the heart, and dreaming.
4. Analyze each option: Increased alertness and hunger are influenced by circadian rhythms but are not rhythms themselves. Dreaming is part of the sleep cycle, an ultradian rhythm. The beat of the heart is a continuous, rhythmic biological process.
5. Conclude which option is a biological rhythm: The beat of the heart is a consistent, rhythmic biological process, making it an example of a biological rhythm.