Answer:
I think it's A) A protein substrate
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The white stringy substance surrounding the fish may be one of these many choices. It could be an <span>euglena, amoeba, </span><span>water mold or </span><span>dinoflagellate. All of these are protists with the same white characteristic.</span>
The nurse should make a note of it so that the doctor will know not to prescribe this particular medicine.
