Final answer:
There is an inverse correlation between a planet's distance from the Sun and its average daytime temperatures: as the distance increases, the temperature decreases. This relationship is due to the decrease in the radiant energy received from the Sun with the square of the distance. Option c is correct.
Step-by-step explanation:
The relationship between a planet's distance from the Sun and its average daytime temperatures is an inverse correlation. As per physics and astronomical observations, the planets' surface temperatures are influenced by the radiant energy from the Sun, which diminishes with the square of the distance. An easy way to visualize this is the fast drop-off in warmth as one moves away from a heat source, such as a fireplace. Within our solar system, planets closer to the Sun, like Mercury, experience much higher temperatures compared to those farther away, like Pluto, which has extremely low temperatures.
The greenhouse effect, which is primarily caused by atmospheric gases like CO₂, also plays a significant role in maintaining a planet's surface temperature. However, the primary factor determining planetary surface temperatures is the distance from the Sun. Earth, our home planet, also experiences a range of temperatures, but life is sustainable due to a balance between its distance from the Sun and a complex atmospheric system, including the greenhouse effect that traps heat.
However, variations in solar activity, such as changes in ultraviolet radiation during a solar cycle, can have other effects on Earth's climate and hence on global temperature. It's essential to note that these effects are relatively small and are subject to ongoing research, and do not significantly alter the overall correlation between distance from the Sun and planetary temperatures.