Deep tillage is even more deleterious to the world' s topsoil supply than previously believed. For example, farmers who till deeply are ten times more likely to lose topsoil to erosion than are farmers who use no-till methods. Results like these make it clear that farmers who now till deeply should strive, by using other topsoil aeration techniques, to incorporate no-till methods instead. The argument depends on assuming which one of the following?
A: In deep-tillage farming, the deeper one tills, the greater the susceptibility to topsoil erosion.
B: Topsoil erosion does not make farmers want to till more deeply.
C: The most expensive farming methods employ topsoil aeration techniques other than deep tillage.
D: Tilling by any method other than deep tillage is not a viable option.
Choose A, B, C or D as your solution.
D