a gre verbal section passage (confusing)
Could anyone help me out? I need a analysis for the passage below:
Recently an unusually high number of dolphins have been found dead of infectious diseases, and most of these had abnormally high tissue concentrations of certain compounds that, even inlow concentrations, reduce dolphins’ resistance to
infection. The only source of these compounds in the dolphins’ environment is boat paint. Therefore, since dolphins rid their bodies of the compounds rapidly once exposure ceases, their mortality rate should decline rapidly if such boat paints are banned.
Question: Which of the following, if true, most strengthens the argument?

C The compounds break down into harmless substances after a few months of exposure to water or air.

The answer is C, but how exactly could C STRENGTHEN the author's argument? I think it's just a presumption, considering the author said "dolphins rid their bodies of the compounds rapidly once exposure ceases". B would be a much better answer for me though.

Question

a gre verbal section passage (confusing)
Could anyone help me out? I need a analysis for the passage below:
Recently an unusually high number of dolphins have been found dead of infectious diseases, and most of these had abnormally high tissue concentrations of certain compounds that, even inlow concentrations, reduce dolphins’ resistance to
infection. The only source of these compounds in the dolphins’ environment is boat paint. Therefore, since dolphins rid their bodies of the compounds rapidly once exposure ceases, their mortality rate should decline rapidly if such boat paints are banned.
Question: Which of the following, if true, most strengthens the argument?

C The compounds break down into harmless substances after a few months of exposure to water or air.

The answer is C, but how exactly could C STRENGTHEN the author's argument? I think it's just a presumption, considering the author said "dolphins rid their bodies of the compounds rapidly once exposure ceases". B would be a much better answer for me though.

Answer

I don't know for certain, as I also think B is strong, but it also reiterates what the author has already said. I think C is also a strong answer because it answers the question of "If the toxins are already in the water, why is banning it useful?". Showing how the animals/marine life will recover after banning is probably important. That would be my best guess.

Answer

These are the rest choices. I removed them because there is a character limit.
A The levels of the compounds typically used inboat paints today are lower than they were in boat paints manufactured a decade ago.
B In high concentrations, the compounds are toxic to many types of marine animals.
D High tissue levels of the compounds have recently been found in some marine animals, but there is no record of any of those animals dying in unusually large numbers recently.
E The compounds do not leach out of the boat paint if the paint is applied exactly in accordance with the manufacturer’s directions.