What is the best pH of the soil for the cultivation of plants:
1.  3.4 – 5.4
2.  6.5 – 7.5
3.  4.5 – 8.5
4.  5.5 – 6.5

Passive absorption of minerals depends on:
1.  Temperature
2.  Temperature and metabolic inhibitor
3.  Metabolic inhibitor
4.  Humidity