GMAT Sentence Correction (SC) | Re: ED FORMS - Verbs or Modifiers

Very succinctly put e-gmat. Kudos.. For the question put up in the topic below was my thought process. Could you please comment if it correct and more importantly could this fail me ?

Q - Scientists have recently discovered what could be the largest and oldest living organism on Earth,a giant fungus that is an interwoven filigree of mushrooms and root like tentacles spawned by a single fertilized spore some 10,000 years ago and extending for more than 30 acres in the soil of a Michigan forest.

A.extending
B.extends
C.extended
D.it
...

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