Fact 1: The looseness of soil increases the amount of oxygen in that soil.

Fact 2: Without oxygen in the soil, most plants die.

Given the two facts above, answer the question "Plants may die without what?" with the following options: 
- nucleus of a cell
 - some looseness in the soil
 - wavelengths and photons
 - moss
 - single-celled organisms
 - organic molecules
 - snow
 - rocks


 

  some looseness in the soil       