Final answer:
The most responsible factors for the distribution of biomes like rainforests, deserts, and grasslands are precipitation patterns and temperature variations, which are integral to an area's climate.
Step-by-step explanation:
The distribution of biomes, such as rainforests, deserts, and grasslands, is primarily determined by climate, which is dictated by patterns of temperature and precipitation. The Earth's major terrestrial biomes are each distinguished by characteristic temperature ranges and amounts of precipitation. These factors directly influence the types of vegetation and animal life found in various regions and are therefore essential in defining biomes.
Tropical rainforests occur where there is high annual rainfall and consistent warm temperatures, while deserts are found in regions of low precipitation, especially near 30 degrees north and south latitudes where descending air creates drier conditions. Grasslands generally exist in areas with moderate precipitation that is not sufficient to support forest growth but is enough to sustain grasses and other herbaceous plants.
In conclusion, climate is the overarching factor that shapes the characteristics and locations of various biomes on Earth, making options B and A the strongest contributors to biome distribution.