Hello Everyone!
Let's tackle this question, one thing at a time, and narrow down our options quickly so we know how to answer questions like this when they pop up on the GMAT! To begin, let's take a quick look at the question and highlight any major differences between the options in orange:
Although the earliest inhabitants of Mapungubwe, building their dwellings of either wattle and daub or unfired mud brick, by the thirteenth century buildings of coral blocks in lime mortar began to appear.
A) earliest inhabitants of Mapungubwe, building their dwellings
B) earliest inhabitants of Mapungubwe, who built their dwellings
C) earliest inhabitants of Mapungubwe built their dwellings
D) dwellings of the earliest inhabitants of Mapungubwe, built
E) dwellings of the earliest inhabitants of Mapungubwe, which were built
After a quick glance over the options, we have 2 main areas we can focus on:
1. “earliest inhabitants” vs. “dwellings of the earliest inhabitants” (Clarity & Modifiers)
2. How each option ends (Construction)
While it may be tempting to start with #1 on our list, we’re going to start with #2.
Why?
Whenever you see almost all of each option highlighted in orange, you’re likely dealing with a “big picture” grammar issue, such as construction, run-ons/fragments, misplaced modifiers, etc. The either/or split in #1 won’t lead us any closer to the correct answer because we’re dealing with something larger. We need to make sure that our sentences have clear subjects and verbs, and that the non-essential phrases (the phrases with commas on either side of them) are truly non-essential to the intended meaning. To make problems easier to spot, let’s add in the non-underlined portions also.
A) Although the earliest inhabitants of Mapungubwe, building their dwellings of either wattle and daub or unfired mud brick, by the thirteenth century buildings of coral blocks in lime mortar began to appear.
This is INCORRECT because it’s a sentence fragment! If we remove the non-essential phrase in the middle, what we have left doesn’t make sense as a standalone sentence. This means the phrase we crossed out actually NEEDS to be there. Any phrase that comes after “although” MUST be an independent clause, but in this case it is not.
B) Although the earliest inhabitants of Mapungubwe, who built their dwellings of either wattle and daub or unfired mud brick, by the thirteenth century buildings of coral blocks in lime mortar began to appear.
This is INCORRECT for the same reason as option A. The “although” statement isn’t an independent clause, and if we remove the non-essential phrase, what’s left over doesn’t work on its own.
C) Although the earliest inhabitants of Mapungubwe built their dwellings of either wattle and daub or unfired mud brick, by the thirteenth century buildings of coral blocks in lime mortar began to appear.
This is CORRECT! The clause that comes after “although” (...the earliest inhabitants of Mapungubwe build their dwellings of either wattle and daub or unfired mud brick…) can totally stand alone as an independent clause. Also, by eliminating the comma before “built,” we don’t have that extra non-essential clause problem!
D) Although the dwellings of the earliest inhabitants of Mapungubwe, built of either wattle and daub or unfired mud brick, by the thirteenth century buildings of coral blocks in lime mortar began to appear.
Again, we have a problem with splitting up the “although” clause into two pieces. Therefore, just like options A & B, this is also INCORRECT.
E) Although the dwellings of the earliest inhabitants of Mapungubwe, which were built of either wattle and daub or unfired mud brick, by the thirteenth century buildings of coral blocks in lime mortar began to appear.
This is INCORRECT for the same reasons as options A, B, and D.
There you have it - option C is the winner! It’s the only option that doesn’t have any issues with the overall sentence construction. By knowing when to focus on “larger” grammar issues, we avoided being distracted by an either/or split that wouldn’t have helped us get closer to the correct choice any faster.
Don’t study for the GMAT. Train for it.