Final answer:
A plant's response to environmental factors like daylight duration and temperature is an example of photoperiodism, illustrating that living organisms interact with their environment. This reflects the unifying biological principle that organisms are responsive to and interact with their surroundings.
Step-by-step explanation:
A plant's response to changes in the length of daylight, temperature, and light quality is an example of photoperiodism. This is a biological response to the timing and duration of day and night, controlling processes such as flowering, setting of winter buds, and vegetative growth. The unifying principle of life that this example illustrates is c) Living organisms interact with their environment.
Plants use systems like phytochrome to detect seasonal changes, which are crucial for survival. Day length is a reliable indicator of time of year, unlike temperature and light intensity, which may vary. Flowering plants, for example, may require exposure to a specific combination of light and dark (photoperiod) or even cool temperatures before responding to photoperiodic cues for flowering.