You are presented with the quiz "What has a positive impact on root growth in dirt?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "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". 

So, what's the best answer to the question?


 

      looseness     