IMO B....Stuart has given a precise explanation.

Cheers

E for answer.

1st split: take vs taking
"taking advantage of off-season demand" modifies "sell the shellfish year-round" => "taking" is correct
=> cross D & E

2nd split: standardize vs to standardize vs standardizing
The correct verb should be parallel with "to sell" and "to predict"

Choose B

E locked.

My answer - E

B

This question tests a couple of important concepts on the GMAT - parallelism and ', + -ing' construction. The latter is typically used to modify or describe an action in the preceding half of the sentence by either indicating the consequence(s) of that action or providing some more information about the action itself.

For example: The volcano erupted, blotting out the Sun.

In the above example, the '-ing' phrase does not refer to the volcano - since a volcano cannot really blot out the Sun - but indicates the consequence of the volcano erupting. In other words, it answers the question of what happened as a result of the volcano erupting - maybe residual ash from the volcano rose up and blotted out the Sun, but the actual volcano almost certainly did not blot out the Sun.

Coming back to the above question, let us first eliminate the options on the basis of parallelism - since we have got the key conjunction 'and', we need the items in the non-underlined portion of the list to be parallel to the underlined portion. Also, note that there needs to be a conjunction (preferably 'and') before the final element of a list of items put in parallel.

For example: John likes to walk, swim, and eat - Parallel
John likes to walk, swim, eat - Not parallel - we need a conjunction before 'eat'

Option A - to sell.., standardize.., and to predict - not parallel - the 'to' needs to be there in front of 'standardize'
Option B - to sell.., to standardize.., and to predict - this is perfectly parallel, so let us hold on to this one for the moment

Option C - In this case, the elements 'to sell.., and to predict' are in parallel; However, there needs to be a conjunction before the 'standardizing' (see above) if 'taking.., standardizing' are to be put in a(nother) parallel list- Incorrect
Option D - to sell.., take.., and to predict - not parallel - the 'to' needs to be there in front of 'take'
Option E - same as D

As we can see, the only option that has got the elements put in parallel correctly is option B. Hence, the correct answer is option B. Let me know in case anything doesn't make sense.