In cold-water habitats, certain invertebrates and fish convert starches into complex carbohydrates called glycerols,
in effect manufacturing its own antifreeze.
(A) in effect manufacturing its own antifreeze
(B) effectively manufacturing antifreeze of its own
(C) in effect manufacturing their own antifreeze.
(D) so that they manufacture their own antifreeze
(E) thus the manufacture of its own antifreeze
I can't understand the meaning of this sentence. My question is: Is "manufacturing ... antifreeze" the result of action "convert" done by invertebrates and fish? If so, then why don't we have structure: "Main clause, Verb-ing" to express the result of the main clause?
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