Manhattan Sentence Correction query - modifiers

[AnupamJ167]

"The country's economy is unstable, the result of a stock market crash that occurred ten years ago."

Above is a sentence from the Manhattan GMAT Sentence Correction book. According to the book, the sentence is correct.

However I have two doubts:
1. We are talking about a specific stock market crash that occured ten years ago - hence should we not use "the" instead of "a"?
2. Are we not skipping "as a" in the original sentence to connect the two clauses? Does skipping this connector not result in a run-on sentence?

According to me, the correct sentence should read as follows:

The country's economy is unstable as a result of the stock market crash that occurred ten years ago.

[RonPurewal]

there's a separate folder for MPrep materials. please post your question in the appropriate folder; thanks.

[RonPurewal]

also, the usage of "a"/"an"/"the" is NEVER tested on this exam—and absolutely never will be. (way too much bias in favor of native speakers of english, and way too much bias against people whose native languages don't have equivalents of these words—e.g., slavic and east asian languages.)

so, any issues involving "a"/"an"/"the" are irrelevant here.