PTF97.S3.Q16: Zebra mussels, a nuisance...

I am a bit confused on why the answer is E and not D. I feel like D makes less of an assumption than E in stating that the algae would clog the pipes and the mussels stop that from being the case. In E, there is mention of transforming the algae. In hindsight, I can sort of see how mussels absorbing hazardous waste would then mean that they themselves are hazardous waste, but I'm having trouble definitively understanding why E is the glaringly right choice over D.

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