Final answer:
Ice caps/glaciers have the highest albedo and reflect the most sunlight among the options provided. Light-colored surfaces like snow and ice are known to have higher reflectivity, and the loss of these due to melting significantly impacts Earth's energy balance and climate.
Step-by-step explanation:
The term albedo refers to the fraction of sunlight that is reflected by a surface, and it is highly influenced by the color and texture of that surface. Surfaces with higher albedo reflect a larger percentage of solar radiation, thus contributing less to warming. Among the given options, ice caps/glaciers have the highest albedo and will reflect the most sunlight. This is because their light-colored surfaces are highly efficient at scattering solar radiation back into the atmosphere.
On the other hand, grassy plains and especially asphalt have much lower albedo. The troposphere, although capable of reflecting sunlight through clouds, does not possess surfaces akin to ice caps in terms of reflectivity. Thus, when thinking about changes in reflectivity and their effect on global climate, the melting of ice caps is a significant concern as it exposes darker surfaces such as ocean water, which absorb more solar energy and further contribute to warming. This is relevant when considering Earth's energy balance and the potential for accelerated global climate change.