What causes color to have a major effect on surface temperature?

The correct choice highlights the role of reflectivity in determining surface temperature. Reflectivity refers to the ability of a material's surface to reflect sunlight. Surfaces with high reflectivity, often lighter in color, can bounce a significant portion of solar energy back into the atmosphere, leading to lower surface temperatures. In contrast, darker surfaces typically absorb more sunlight, converting it into heat and resulting in higher surface temperatures.

For instance, a white or light-colored roof will reflect a greater amount of sunlight compared to a dark roof, which absorbs more heat. This principle is especially critical in urban environments, where "cool roofs" can help mitigate the urban heat island effect.

In this context, thermal conductivity, the weight of the material, and moisture retention do not have the same direct impact on how color influences surface temperature. While thermal conductivity may affect how heat moves through materials, it does not directly relate to color’s impact on reflectivity. Similarly, the weight and moisture retention of a material do not significantly affect its ability to reflect light and, thus, its surface temperature.