I'm looking at this question:
Which of the following most logically completes the argument?
Using new detection techniques, researchers have found trace amounts of various medicinal substances in lakes and rivers. Taken in large quantities, these substances could have serious health effects, but they are present in quantities far too low to cause any physiological response in people who drink the water or bathe in it. Nevertheless, medical experts contend that eliminating these trace amounts from the water will have public health benefits, since ____________.
some of the medicinal substances found in lakes and rivers are harmless to humans in large quantities
some of the medicinal substances found in lakes and rivers can counteract possible harmful effects of other such substances found there
people who develop undesirable side effects when being treated with medicines that contain these substances generally have their treatment changed
most medicinal substances that reach lakes or rivers rapidly break down into harmless substances
disease-causing bacteria exposed to low concentrations of certain medicinal substances can become resistant to them
We are essentially looking for an answer that favours the removal of such medicinal substances.
I saw (C) and (E) as such examples. However, why would E be considered a stronger choice than C?
Thanks for all your help.