Q: Fact 1: The looseness of soil has a positive impact on a plant 's roots' growth in that soil. Fact 2: Soil or dirt is typically high in silica and alumina. Given the two facts above, what has a positive impact on root growth in dirt?

Possible answers:
1). nutrients
2). burrs
3). exercise
4). support
5). evaporation
6). looseness
7). Sand dollars
8). sun's heat
The answer is:
6).