In earlier times farmers made cheese mainly to preserve perishable

Not sure but guess B only.

I think it is so because : means same thing in another words.
so we can't talk of way of shipment / shipment itself

we have to talk about dairy product only.

In earlier times farmers made cheese mainly to preserve perishable milk and to reduce its bulk : this was how the output of dairy herds could be shipped in this form to distant urban markets.

Lets break the sentence:

Clause 1: In earlier times farmers made cheese mainly to preserve perishable milk and to reduce its bulk - Farmers is subject and made is verb`
Clause 2: this was - this is subject and was is verb : This can not be used independently, it can be used with a noun. eg. this cheese
Clause 3: how the output of dairy herds could be shipped in this form to distant urban markets - the output is subject and could be is verb, this form is used correctly

a)

b) the output of dairy herds could, in this form, be shipped to distant urban markets. - This is correct sentence . "the output" correctly modifies cheese.

c) it was a form of shipping the output of dairy herds to distant urban markets - This is a new clause which can not be separated by : from main clause.

d) there was a way to ship the output of dairy herds in this form to distant urban markets - Same error as B and focus shift on way from output

e) shipment of the output of dairy herds to distant urban markets was done in this form. This also shift the focus of sentence and this is a new clause connected imprperly

The pronoun "this" can't go alone, it needs to mention something like "this way", "this form", etc. The same goes to THESE or THERE.

Would anyone shed some light on the issue that pronouns and demonstrative pronouns can or cannot be used for the clauses?

Thank you

There are four demonstrative pronoun/adjectives - This (Singular) ,That (Singular) ,These (Plural) ,& Those (Plural)

In the example (as in many cases of written English) - This is used as "demonstrative adjective" . Thus, "This" must be followed by NOUN.

Pay particular attention to the colon ":"

As a rule, we can't put an independent clause (a clause that could stand on its own, has a subject and a predicate) after ":"


a) this was how the output of dairy herds could be shipped in this form to distant urban markets. --- independent clause, could stand on its own
b) the output of dairy herds could, in this form, be shipped to distant urban markets. --- dependent clause!
Let's eliminate the garbage:
The

c) it was a form of shipping the output of dairy herds to distant urban markets --- independent clause, could stand on its own
d) there was a way to ship the output of dairy herds in this form to distant urban markets --- independent clause, could stand on its own
e) shipment of the output of dairy herds to distant urban markets was done in this form. --- independent clause, could stand on its own

I didn't understand why are we rejecting option C. "IT" in option C can act as placeholder and option C conveys meaning properly. Can anyone please help me to understand what i am missing in above SC question.

Ironically, even placeholder it has its antecedent.

E.g. It was Garry who took my icecream It=who took my icecream was Garry OR It=Garry was who took my icecream
It is Thailand that has beautiful nature It=that has beautiful nature is Thailand.

Even if Garry is a person we use it - one of the rare cases when it can reffer to a person. C'est la vie...

Now option C: It was a form of shipping the output of dairy herds to distant urban markets
It=form of shipping was a form of shipping ... Well, form of shipping was a form of shipping doesn't make sense.

In case if it's not a placeholder then it = milk because in the first part we have already used its for milk. Even so milk was a form of shipping - doesn't make sense

Just adding another issue here.

"in this form" is a misplaced modifier and it is moving all around the answer choices, except for C. This modifier should be close as possible to "the output of dairy herds". By noting this modifier issue only, you would be able to eliminate A, C and E, and chose between B and D. Misplaced modifier is a very common topic on GMAT.

The greatest problem with A is that 'this was how" and 'in this form' are redundant. We can say either

this was how the output of dairy herds could be shipped to distant urban markets.

or

the output of dairy herds could be shipped in this form to distant urban markets.

Isn't "this" in (B) is used as pronoun instead of article?

Here's the official explanation provided by the GMAC for this question:

Option A: The sentence is meant to explain why farmers in earlier times began making cheese. However the underlined portion contains redundancy that makes it wordy, confusing, and unnecessarily awkward. The sentence would be much clearer if this was how were omitted, given the later phrase in this form, refers to the cheese form of dairy output.

Option B: Correct. This version contains none of the flaws noted above. Moreover, placing in this form immediately following could is a rhetorical improvement; it indicates more precisely that the possibility signaled by could arose from the transformation of dairy output into cheese.

Option C: What it refers to is quite unclear (for example, it makes no sense to say that making cheese was a form of shipping). The phrase form of shipping would reasonably be read as implying a contrast between modes of transport (for example road transport versus river transport), but this is inapplicable here.

Option D: This version tells us, in effect, that the output of dairy herds could be shipped to distant markets. But this fails to capture a crucial point of the explanation: that it was practical to ship dairy output to distant markets only in the form of cheese. In this context, the phrase there was a way is wordy and unnecessarily awkward.

Option E: This version omits the notion of possibility signified by could. The form shipment … was done is awkward and offers no improvement on the verbal form could be shipped.The wording also nonsensically suggests that cheese was a form in which shipment was done, rather than a form in which the output of dairy herds was shipped.

The correct answer is B.

Please note that I'm not the author of this explanation. I'm just posting it here since I believe it can help the community.

Are there two versions of this question?
Because the one that is included in the official practice pack 2 , has a semi-colon instead of a colon.

Hello Sir,

i have a doubt.

the sentence "this was how the output of dairy herds could be shipped to distant urban markets." mentioned by you have "this" in it.

Isn't this is a demonstrative noun here and must be followed by noun.

Please shed some light on this.

Thank you sir

Bunuel Hi Bunuel, In the original question there is no colon but semi colon. Its good if you can just update colon to semi colon to avoid confusion for others.

________________________
Fixed that. Thank you!

In earlier times farmers made cheese mainly to preserve perishable milk and to reduce its bulk: this was how the output of dairy herds could be shipped in this form to distant urban markets.

What follows the colon is the list, explanation, and example.
E.g., The reason for his absence was simple: he had fallen ill.

In our example, we are looking for an explanation of the earlier clause - here, "the output" correctly refers to cheese converted from perishable milk and reducing its bulk.

(A) this was how the output of dairy herds could be shipped in this form to distant urban markets - "this" pronoun refers to an action of making cheese - wrong. Moreover, after this, we need a noun. E.g., This book is interesting. Moreover, "this was how" and "in this form" are redundant.

(B) the output of dairy herds could, in this form, be shipped to distant urban markets - ok. Here, "the output" correctly refers to cheese converted from perishable milk and reducing its bulk.

(C) it was a form of shipping the output of dairy herds to distant urban markets - "it" refers to cheese. Cheese was a form of shipping? Also, it has an ambiguous reference.

(D) there was a way to ship the output of dairy herds in this form to distant urban markets - There is a shift from the "output," which is "cheese," to "the way to ship." The intended meaning is that this was the only way. The information after the colon should be additional to what has been said in an earlier clause before the colon. So after the colon, we need to focus on the "output" or "cheese" and not on the "way to ship."

(E) shipment of the output of dairy herds to distant urban markets was done in this form - The same issue as in D. There is a shift from the "output" to "the way to ship." As ChiranjeevSingh pointed out, it suggests that cheese was a form in which shipment was done, rather than in which the output of dairy herds was shipped.