Winner2013 wrote: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 rootlike 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 extended
(E) is extending

A should be the correct answer here. extending is used as a gerund which is correct.

This is a Blind parallelism example:

"spawned" is an Adjective.. we need another adjective and NOT VERB

{A} - CORRECT; Adjective
{B} - INCORRECT; VERB
{C} - INCORRECT; since the discovery is recent.. "extending" is correct
{D} - Incorrect; redundancy
{E} - INCORRECT; redundancy

so is it tentacles that they are talking about while using adjective extending?

can you clarify?

thanks for your inputs

Winner2013 wrote:so is it tentacles that they are talking about while using adjective extending?

can you clarify?

thanks for your inputs

Nope...
a giant fungus ....................... spawned by a single fertilized spore some 10,000 years ago and extending

This is one of the trickiest OG questions. The parallel marker and tells you that extending ( or whichever word or phrase ends up after and) must be parallel to something earlier in the sentence. That something is spawned.

Both spawned and extending are what are called participles, words that are ordinarily verbs but are put to work as modifiers. Participles can be either noun modifiers (effectively adjectives, theCodeToGMAT suggests) or adverbial modifiers. In this case they're meant to modify filigree.

Spawned is what is called a past participle while extending is what is called a present participle. In spite of these labels, though, the tense of the participle doesn't reliably tell you anything about the order of events. Rather, past participles are passive and present participles are active. Spawned is correct because it tells you that something was done to the filigree, it didn't spawn, it was spawned. Extending is correct because it tells you that the filigree did something, it wasn't extended, it did extend.

Bottom line: parallel participles need not have the same tense. (Lagniappe: parallel verbs need not have the same tense either! But that's a subject for another post.)