In addition to frequent fires the factors that maintain grass land biome are:

Explanation

Grassland biomes are maintained by several factors including low rainfall, which limits tree growth and encourages grasses to thrive. Grazing by animals is another crucial factor as it helps control plant growth and maintain the grassland ecosystem. While high temperatures are common in grasslands, acidic soils are not typical. Hence, the correct answer is low rainfall and grazing by animals. Other options are incorrect because they either include conditions not typical to grasslands or are incomplete in describing factors that maintain the biome.