Hello Everyone!
Let's tackle this question, one issue at a time, and figure out the easiest way to get to the right answer! Before we dive in, here is the original question with any major differences between the options highlighted in orange:
It is called a sea, but the landlocked Caspian is actually the largest lake on Earth, which covers more than four times the surface area of its closest rival in size, North America's Lake Superior.
(A) It is called a sea, but the landlocked Caspian is actually the largest lake on Earth, which covers
(B) Although it is called a sea, actually the landlocked Caspian is the largest lake on Earth, which covers
(C) Though called a sea, the landlocked Caspian is actually the largest lake on Earth, covering
(D) Though called a sea but it actually is the largest lake on Earth, the landlocked Caspian covers
(E) Despite being called a sea, the largest lake on Earth is actually the landlocked Caspian, covering
After a quick glance over the options, we see that there are a few places where we can focus our attention:
1. The modifier in the beginning: It is / Although / Though / Despite
2. Placement of the word "actually"
3. The modifier at the end: which covers / covering / covers
Since we're dealing with modifiers, let's do a quick check to make sure all the modifiers are placed directly before or after the word(s) they're referring to. This is one of the most common modifier errors on the GMAT, so it's a good place to start:
(A) It is called a sea, but the landlocked Caspian is actually the largest lake on Earth, which covers
This is INCORRECT because the modifier "which covers more than four times..." is placed next to "Earth," which is NOT what it's supposed to modify! This means we have a misplaced modifier, which is a big no-no on the GMAT!
(B) Although it is called a sea, actually the landlocked Caspian is the largest lake on Earth, which covers
Again, this is INCORRECT because it suggests that the modifier should be tied to Earth, rather than the Caspian, which it should be referring to.
(C) Though called a sea, the landlocked Caspian is actually the largest lake on Earth, covering
This is OKAY because when you begin a modifier with an -ing word, it's now modifying the entire phrase, rather than just the subject closest to it.
(D) Though called a sea but it actually is the largest lake on Earth, the landlocked Caspian covers
This is INCORRECT because we have a misplaced modifier and some terribly awkward wording. The modifier "but it actually is the largest lake on Earth" seems to be in the wrong place - it would make more sense to put it directly after "the landlocked Caspian" to make it clear that's what it's referring to. By removing the comma before "but," it also sounds like a run-on sentence, rather than a modifier.
(E) Despite being called a sea, the largest lake on Earth is actually the landlocked Caspian, covering
This is OKAY because when you begin a modifier with an -ing word, it's now modifying the entire phrase, rather than just the subject closest to it.
We can eliminate options A, B, and D because they have problems with misplaced, confusing, and poorly written modifiers.
Now that we only have to focus on options C and E, let's focus on any overly wordy or confusing phrasing:
(C) Though called a sea, the landlocked Caspian is actually the largest lake on Earth, covering
This is CORRECT! Starting with "Though" is clear and concise, and it makes a bit more sense to place the Caspian first in the next clause because it creates a clearer contrast to " called a sea."
(E) Despite being called a sea, the largest lake on Earth is actually the landlocked Caspian, covering
This is INCORRECT for a couple reasons. First, the GMAT prefers writers avoid the "being + verb" combination whenever possible. It's overly wordy, and there is almost always a better way to phrase it. Second, it makes more sense to put the Caspian first in the next phrase. The modifier in the beginning is "Despite being called a sea," and whatever comes next should be what is called a sea - the Caspian.
There you have it - option C is our best choice!
Don't study for the GMAT. Train for it.