The looseness of soil has a positive impact on a plant 's roots' growth in that soil, and soil or dirt is typically high in silica and alumina. Given these facts, what has a positive impact on root growth in dirt among the following options:
- nutrients
 - burrs
 - exercise
 - support
 - evaporation
 - looseness
 - Sand dollars
 - sun's heat


 

      looseness   