Re: Ancient Thailand

Dear WaterFlowsUp,
I'm happy to respond. BTW, I like your paradoxical screenname.

Question #1: yes, choice (A) is a trainwreck on a number of grounds. The "when" clause is a blatant violation of parallelism, so that's just as good a reason to reject it as is the idiom mistake.

Questions #2: the "-ing" form of a verb has three potential roles
(a) part of a present progressive verb
http://magoosh.com/gmat/2012/gmat-verbs ... ive-tense/
(b) a participle (i.e. a modifier)
http://magoosh.com/gmat/2012/participle ... -the-gmat/
(c) a gerund (which acts as a noun)
http://magoosh.com/gmat/2012/gmat-gramm ... d-phrases/
In choice (D) the word "creating" is a gerund, and in fact, the gerund phrase "creating images of Buddha" is the subject of the verb "accounted".
This post discusses distinguishing these three easy-to-confuse grammatical constructions:
http://magoosh.com/gmat/2012/the-ing-form-of-a-verb/

Questions #3: because the parallelism is faulty in many of the incorrect choices, I will diagram the parallelism in choice (B), the OA. First, here's the whole sentence:
In ancient Thailand, much of the local artisans creative energy was expended on the creation of Buddha images and on construction and decoration of the temples in which they were enshrined
Now, an attempt at a clear diagram ----
(main clause of sentence:) In ancient Thailand, much of the local artisans creative energy was expended
(first branch of parallelism:) on the creation of Buddha images
(conjunction linking the two parallel branches:) and
(second branch of the parallelism:) on construction and decoration of the temples in which they were enshrined

Both branches of the parallelism begin with the preposition "on", and the words in dark green are the parallel words. Notice, all three here are "-tion" nouns, whereas in incorrect answer choices, some are "-tion" noun while others are gerunds or phrases.

Does this make everything clear and answer all of your questions?
Mike