Hi prachi18oct,

The big clue in this SC is the last 2 words in the sentence: "....under it." Since we can't change those words, we have to make sure that the rest of the sentence makes sense AND ends with those two words.

We're clearly dealing with a comparison; the words "more babies.....than...." provides the comparison. Comparisons almost always involve Parallelism rules, so we need to consider that....

".....under it." is supposed to be parallel to what?
".....over it....."

Here, the phrase "...over the age of thirty..." is later followed by the parallel phrase "...under it...." ("it" refers to "the age of thirty"). These elements ARE parallel, so we don't really need to include any additional words.

The sentence COULD have been written in the following way: "more babies were born to women over the age of thirty than to women under the age of thirty." That option is NOT in the answer choices though - also notice that it includes redundant language that the GMAT tends to remove from a correct answer.

The correct answer just needs to complete the Comparison phrase. The word "than' is all that's needed.

Final Answer: A

GMAT assassins aren't born, they're made,
Rich