Help me please asap :D Will give BRAINLIEST and 5 STARS!! Thank you!

In an area with tall grass but with very few trees, which of the following other conditions are most likely to exist as well?
1 It is near 30° latitude north or south or on the leeward side of a mountain range. 2 Moist air is rising over the area.
3 Night temperatures are much colder than daytime temperatures.
4 The soil has a thick layer of decomposed, nutrient-rich organic material.
5 There is an extremely high diversity of species in the area.
6 There is little rainfall and frequent fires regularly cut the vegetation to the ground.

a 2 and 5
b 3 and 4
c 1 and 3
d 4 and 6