While many people believe either lead or gold is the densest naturally

OFFICIAL EXPLANATION



In the Magoosh OE, I edited just a few items.
All the paragraphs before the Comments section are from Magoosh.
Everything in and after the Comments section is from me. (The footnote is in blue typeface to signal that I inserted that note.)

MAGOOSH Official Explanation

Option A
Choice (A) illogically suggests that osmium itself, the very existence of the element itself, is "due to a pattern of density among the elements."
Furthermore, the final three words of (A) are a disaster.
Those three words are they call it:
→ (a) who is "they"? This pronoun has no antecedent in the sentence; and
→ (b) the antecedent of "it" is grammatically ambiguous. That antecedent could be osmium, or the pattern, or the distinction.
(A) is incorrect.
Eliminate A.

Option B
Choice (B) uses the emphatic construction.**
[This construction is] appropriate, because osmium is contrary to many peoples' expectations on this question.
The rest is grammatically correct. This is a promising choice.
KEEP B

Option C
The section before the underlined section is a subordinate clause beginning with while, so the independent clause, the main clause of the sentence, must come in the underlined section.
Choice (C) has no verb, and thus would create a sentence with no verb.
This is the missing verb mistake. (C) is incorrect.
Eliminate C.

Option D
Choice (D) has an odd construction.
After the initial subordinate clause, it has a noun + modifier "osmium, holding this distinction," then a conjunction and an independent clause. This has the effect of leaving "osmium" as a free-floating noun in the sentence, not part of any clause.
Furthermore, the "for" clause would introduce an explanation, but here, it illogically suggests that what the pattern is called, not the pattern itself, is the explanation of osmium's properties. (D) is incorrect.
Eliminate D.

Option E
Choice (E), like choice (C), has no verb, and thereby creates a sentence with no main verb.
Furthermore, the "because" clause suggests illogically that what the pattern is called, not the pattern itself, is the explanation of osmium's properties. (E) is incorrect.
Eliminate E.

The only possible answer is (B).

Frequently Asked Questions:

FAQ: How can we distinguish between "due to" and "because of" in this question?

A: Great question! The phrase "due to" must modify a simple noun (a person, place, or thing), while the phrase "because of" must modify a verb.

Here's a great Magoosh GMAT blog post discussing the distinction:

The phrase due to is similar to but not interchangeable with because of.
n colloquial use they [i]are used interchangeably, but there is a subtle difference.
The words because of are a compound preposition, and the preposition phrase formed can modify the verb and thus be placed in any part of the sentence.
The word due is an adjective and must modify a noun.
Let's take a look at some examples:

She did well (verb) on the test because of her hard work and diligence.
We use "because of" here because it modifies the verb "did well."

Her success (noun) on the test was due to her hard work and diligence.
The "due to" here modifies the noun "success."
[Note: can you substitute caused by or attributable to for due to? If so, due to is almost always correct.]

So "due to" modifies a noun, whereas "because of" has to modify a verb.

COMMENTS

zhanbo , I suspect that Mike McGarry inserted the comma in option B because the construction is emphatic (see my footnote) and he felt that the comma was necessary to highlight or preserve that construction. Or perhaps he decided to subordinate the "avoid placing a comma after a dependent clause that comes midsentence" rule to what he, a highly trained writer fully fluent in the style of the English language, thought would present the clearest sentence.
I will not remove the comma, though I do understand your concerns about the rule to which you tacitly refer. (In this fairly standard collection of comma rules, it's number 15.)

Sohinik , welcome to SC Butler. We are very glad to have you.

This question is slippery.
Aspirants, do not worry if you missed it—next time you will not fall for whatever trap ensnared you this time.
(Or, if you get ensnared again, keep going. Eventually the knowledge will solidify.)

These answers handle this slippery question quite well.
Nice work!


*The emphatic "it" is constructed with this template: It is A that does X/ that is B.
We say that this "it" structure is emphatic because it is used to emphasize a subject, and object, or even an adverbial modifier.
Suppose that a father hollers from the living room to one of his two children to "turn down the blasted music."
That child, Sarai, is not the one playing the music.
Sarai replies, "It is Avi who is blasting the music."
Sarai is saying that her brother is playing the loud music—not she.

You can read a very short piece about different ways that the word "it" is used.
Scroll down and read the examples under "Emphatic It," after clicking here.