Answer:
I'm not completely sure but my best guess would be the 3rd one
Begin to spin around a LOW-pressure center!
Ploughing and turning over the soil aerates the soil so the roots of plants are able to thrive well. Ploughing the roots of leguminous plants back to the soil returns nutritents and organic matter to the soil organically rather than using synthetic fertilisers which are potentially hazardous to the environment.
Explanation:
But two water molecules contain four hydrogen atoms, which means that two hydrogen molecules must be present on the reactant side of the equation for the numbers of H atoms to balance (Figure 7.2 on the previous page).