Sentence Correction

Scientists have recently discovered what wcould be the largest and oldest living organism on Earth, a giant fngus that is an interwoven filigree of mushrooms and rootlike tentacles spawned by a single fertilized spore some 10000 yrs ago and extending for more than 30 aces in the soil of a michigan forest.

a. extending
b. extends.
c. extended
d. it extended.
e. is extending

Why is A parallel with Spawned? Why not B? Both mean that they are today in this state of extension. but 1 means that it is still extending, and the other just says its in a current state of extension, it seems to me that both could be parallel.

also.. does E not work because there is the "is"? if it said "was spawned" than does it mean that E would have been the right answer?

thanks

ray

Scientists have recently discovered what would 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 10000 yrs ago and extending for more than 30 aces in the soil of a Michigan forest.

Read the sentence without the blue part

a. extending - Makes sense
b. extends - Awkward
c. extended - Past
d. it extended
e. is extending - Present continuous

IMO: A

CONTINUITY...takes us to the present participle

(A)