Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil, their descendents, popular known as killer bees had migrated as far north as Southern Texas.
A. Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil,
B. In less than 35 years since releasing African honeybees outside Sao Paulo, Brazil,
C. In less than the 35 years since African honeybees had been released outside Sao Paulo, Brazil,
D. It took less than 35 years from the release of African honeybees outside Sao Paulo, Brazil, when
E. It took less than 35 years after the time that African honeybees were released outside Sao Paulo, Brazil, and then

C sounds correct because the release of the honeybees preceded the migration of its descendants and both the actions took place in the past. Therefore, the release should be "had been released" and the "migrated" as correctly written is "had migrated"

Could anyone eplain why A?
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A for me too...
B and C are eliminated because "since" is used....
E is wordy and "after the time" is not proper....
D is incorrect because of the usage of 'when'...

A. ..after the release .. had migrated
B. ..since releasing .. had migrated
C. ..had been released .. had migrated
D. ..from the release .. had migrated
E. ..were released out.. had migrated

all the options apart from A have tense agreement problem

Let me give you my humble opinion.

B incorrect because, in part, of the misplaced modifier rule: whatever "releasing" is referring to needs to follow the comma after Brazil. However, "their descendants" (of honeybees) is unacceptable for obvious reasons.

C incorrect because "since" must be followed by an event at a particular point in time in the past (i.e, since 2000; since the release of the honeybees, since the honeybees were released). For this reason, the past perfect is inappropriate and you must use the simple past if you opt for a conjugated verb. Do NOT use the past perfect in the "since" clause, period. Also using "the" before 35 years is incorrect.

D and E incorrect:
D and E do not need any serious discussion as they offer an awkward sentence construction not used in English. Avoid that construction at all times (it... ,when or it...,and then)
Also "from" in D and "after the time" are not adequate in this context.

A is the correct answer.
Less than 35 years is enough-No need of the beginning "in".
A great way to check whether A is correct is to have the two clauses switch places; begin with the main clause "their descendents, popular known as killer bees had migrated as far north as Southern Texas and finish with the subordinate clause "less than 35 years after the release of African honeybees outside Sao Paulo, Brazil". This gives us:

Their descendents, popularly known as killer bees, had migrated as far north as Southern Texas less than 35 years after the release of African honeybees outside Sao Paulo, Brazil.
This is indeed a correct sentence.

Now, try the same technique with the other choices and tell us whether you like the resulting sentence. Which seems the most natural and fluid to you?
Finally, if A ain't broken, don't try to fix it.

I hope this helps.
Bye now.
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TheGMATDoctor, could you please elaborate why D and E are wrong. TIA

A. Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil, :Correct form
B. In less than 35 years since releasing African honeybees outside Sao Paulo, Brazil,: seems as if the descendant killer bee is the agent - they released african honeybees!! (releasing here is functioning as a participle, not a gerund)
C. In less than the 35 years since African honeybees had been released outside Sao Paulo, Brazil,: passive voice, not prefered form
D. It took less than 35 years from the release of African honeybees outside Sao Paulo, Brazil, when :Use of IT is unnecessarily wordy - from the release of is wrong construction.
E. It took less than 35 years after the time that African honeybees were released outside Sao Paulo, Brazil, and then: Unnecessarily splits the sentence into two independent clauses joined with a comma- it took....and then...less than 35 years after the time is wrong

One doubt here

past perfect tense always pairs with a past tense to indicate the relative time difference between 2 events occured in the past .

But (a) doesn't have a past tense, only a past perfect ...
Am I missing something here
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