SAT Question 97e7bedc: Form Structure And Sense answer and explanation

English - Form Structure And Sense - Subject Verb Agreement
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Oyster mushrooms typically get their nutrients from the damp logs on which they grow, but the fungi are also carnivorous, with the ability to kill and consume microscopic worms known as nematodes. As researcher Yen-Ping Hsueh has shown, the mushrooms release a toxin that is deadly to nematodes that ______ in contact with it.
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Difficulty:Medium
Which choice completes the text so that it conforms to the conventions of Standard English?