The correct answer is grass growth increase.
The wildfire in the grassland can help to improve the soil quality there. There are many positive sides of the wildfires. One of them is that it helps to improve the soil quality and favors the growth of plants there.
As the area is grassland, there will be growth of the grasses.
In case of wildfires, the contaminated soil gets burned and the harmful microorganisms die due to the fire and this improves the quality of the soil which ultimately grows the grass.