题目内容:
Researchershavemetwithdifficultieswhentryingtomakealgaeproducehydrogenefficiently.Whichoneofthefollowingisonesuchdifficulty?_______A Itisnotpossibletoremovesulfatefromtheenvironment.
B Itisnotpossibletoworkinanairfreeenvironmenttoproducehydrogen.
C Itisnoteasytomakesugarsinsteadofhydrogen.
D Itistooslowforalgaetoproducehydrogenwhenthesulfateisremoved.
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