OG 10 question

Dear hey_thr67,

Hi, there. I'm happy to help with this.

One distinct that you may find helpful is the distinction of a vital vs. non-vital noun modifier. Here's a blog that explores that distinction:
https://magoosh.com/gmat/2012/gmat-gramm ... modifiers/

As a general rule, if the modifying preposition is a vital noun modifier, than any pronoun will include the vital modifier as part of the antecedent. If the modifier is not vital, in general the pronoun will not include it as part of the antecedent.

Here, the phrase is "rate of addition" --- the proposition "of addition" is vital, because without it we have absolutely no idea what rate, even what kind of rate, is being discussed (interest rate? rate of speed? exchange rate? etc.) Therefore, the proposition "of addition" is vital", and therefore, in (B), the pronoun "it" refers to "rate of addition", not simply to "rate."

Also, just a note on parallelism. On the GMAT SC, parallelism ALWAYS involves the same preposition. We had a "rate of addition to arable lands", so its guaranteed that we need the same preposition, "of", in the parallel construction. That is a completely certain GMAT SC feature that will show up time and time again. Eliminating by preposition only narrows the answer choices down immediately to just (C) and (D), and (C) can't be right because "rate" is singular and "those" is plural.

Does all this make sense?

Here's another tricky SC question, involve a pronoun.
https://gmat.magoosh.com/questions/1088
When you submit your answer, the following page will have the complete video explanation.

Let me know if you have any further questions.

Mike