by dbernst Mon Aug 20, 2007 8:37 pm
Luci, answer choice C awkward and wordy. By beginning with when, this choice implies that the time of the comet's disintegration was the most pertinent factor for scientists, rather than the disintegration itself. Choice C is also redundant by stating may possibly force. Since possibly simply means may, there is no reason to use both words. Conversely, choice A clearly uses the more standard and clear Subject - Verb - Object (The disintegration provided new insights) sentence structure.
As for your question about hyphens, they are used to connect words that directly relate to one another. For non-native English speakers, this might seem somewhat confusing, especially since English contains a nearly identical punctuation mark - the dash - that is used to provided emphasis or clarification. Fortunately, the GMAT is not a test of punctuation and thus will never base a correct answer choice on one of these grammatical structures.
Hope that helps.
-dan