I think the conclusion here is:
-- the mixture works as a miracle cure because it can destroy tumors while revitalizing living tissue.
Premise:
The doctors believed the extract could:
- kill parasites
- destroy tumors
- revitalize living tissue
Why B is correct:
Option B says tumors are themselves living cells, and the mixture would affect tumors the same way it affects living tissue.
That creates the flaw directly.
If tumors and living tissue are affected in the same way, then the mixture cannot both:
- destroy tumors
and
- revitalize living tissue
That is the contradiction in the argument, so B attacks the logic at its core.
Why I eliminated the others:
A:
Only talks about making the extract safer by dilution. It does not weaken the actual reasoning.
C:
Very broad statement about medication in general. It does not specifically attack this argument.
D:
Talks about healthcare costs, which is outside the logic of the cure itself.
E:
This one looked tempting initially, but it only introduces a side effect (metabolism/diet changes). A treatment can still work even if side effects exist, so it does not expose a flaw in the reasoning.
So for me, B directly exposes the internal contradiction, while E only discusses a possible consequence.
— Rajdeep