The blown film technique which inflates huge bubbles in

OFFICIAL EXPLANATION

OFFICIAL EXPLANATION

This sentence gives two different types of information about the "blown film" manufacturing technique:
(1) how it works (a bubble is blown in a mass of molten plastic, causing the plastic to expand), and
(2) what it can produce (exceptionally large plastic sheets or tubes).

The sentence should be phrased in a way that makes these relationships clear, with modifiers used appropriately.

(A) The modifier which inflates… applies to the preceding subject, the “blown film” technique, thus illogically suggesting that the technique itself, rather than some machine or its operators, can inflate bubbles. The modifier in order to expand applies to the preceding clause (which inflates huge bubbles…), suggesting the nonsensical notion that the blown-film technique itself is trying to expand.

Furthermore, has the capability to produce is not as concise as the phrase can produce.

(B) The initial modifier By inflating… applies to the following subject, the “blown film” technique, , thus illogically suggesting that the technique itself, rather than some machine or its operators, can inflate bubbles.

Again, has the ability to produce is not as concise as can produce.

(C) The portion of this choice before the semicolon is a sentence fragment; it consists only of a noun phrase (the "blown film" technique), preceded and followed by modifiers.

Furthermore, as a result of the rearrangement of words at the end of this choice, the modifier in which the process occurs now illogically modifies the building's size rather than the building.

(D) CORRECT.
The modifier in which… is properly used to describe the blown-film technique.

The passive is inflated is correctly used to describe the inflation of the bubble, as the actual mechanism that inflates the bubble is not mentioned (nor is it important) in the sentence.

The modifier causing the plastic to expand correctly describes an immediate consequence of the action in the preceding clause.
Overall, the core sentence states logically that The blown-film technique… can produce a plastic sheet or tube with the characteristics described.

(E) The modifier Involving huge bubbles…, while grammatically valid, is unacceptably vague: it states only that the blown-film technique involves such bubbles (in some capacity). In other words, this sentence allows for the possibility that the blown-film technique uses bubbles produced arbitrarily in some other, unnamed, process, rather than that the generation of the bubbles is a fundamental aspect of the blown-film technique.

The modifier that is capable of… modifies a plastic sheet or tube; while this modification is also grammatically acceptable, it doesn't make sense, as it implies that the plastic sheet or tube might change sizes (up to some maximal capability) once it has been produced.

An entire building should be the entire building, as the sentence is meant to convey the idea that the plastic sheet or tube can have the size of the building in which it is produced; an entire building in which the process occurs instead refers, illogically, to an arbitrarily chosen building equipped for the blown-film process.

Finally, as a result of the rearrangement of words at the end of this choice, the modifier in which the process occurs now illogically modifies building's size rather than building.

The correct answer is (D).