In the past decade, a decreasing percentage of money spent on treating disease X went to pay for standard methods of ...

I am still confused as to how D isn’t correct because by spending money on the nonstandard which is cheaper & ineffective you would think that it makes the argument sufficient because they are going the cheaper route when when they should be budgeting instead for the standard method. So with every purchase of the nonstandard is less money spent that should be actually spent for the standard treatment.