basic assumption

Hi

A certain experimental fungicide causes no harm to garden plants if it is diluted at least to ten parts water to one part fungicide. Moreover, this fungicide is known to be so effective against powdery mildew that it has the capacity to eliminate it completely from rose plants. Thus this fungicide, as long as it is sufficiently diluted, provides a means of eliminating powdery mildew from rose plants, without entailing any risk of harm to the other garden plants.

Which of the following is an assumption on which the argument depends?

A. There is no alternative method to application of fungicide for eliminating powdery mildew from rose plants without harming other garden plants.

B. When the fungicide is sufficiently diluted, it does not pose any harm to people, animals, or beneficial garden insects.

C. Powdery mildew is the only fungal infection affecting rose plants.

D. There are no antidotes available if the fungicide is not sufficiently diluted inadvertently.

E. The effectiveness of the fungicide on powedery mildew does not depend on its concentration levels greater than one part in ten parts of water.

Thanks