What we are tested on here is the correct usage of the idiom “not only X, but also Y” in which X and Y must be parallel.
A. to investigate not only whether research is an independent aspect at brokerage companies, but also whether disputes result when analysts own the stocks they write about or when they are
This one has a correct parallelism with two similar noun clauses: to investigate not only X, but also Y
X = whether research is an independent aspect at brokerage companies
Y = whether disputes result when analysts own the stocks they write about
There are other two parallel elements that make choice A superior: disputes results when X or when Y
X = when analysts own the stocks they write about
Y = when they are paid for their work…
B. to investigate not only whether research is an independent aspect at brokerage companies, but also
if disputes result when analysts own the stocks they write about
or they are1. we can see that “whether clause” and “if clause” are not as parallel as choice A’s similar elements are. The reason is that “whether clause” is a noun clause that is the object of the verb “investigate”, as in “investigate something”. However, “if clause” is not a noun clause, but a conditional marker, so it cannot be the object of the verb “investigate”.
2. in simple words, we cannot write “to investigate if disputes result” as to investigate something. So such usage is wrong.
3. because the second “when” misses after “or”, this sentence is not as easily readable as choice A. We will have to reread it several times before we get the core meaning.
C. to not only investigate whether or not research is an independent aspect at brokerage companies, but also
if disputes result when analysts own the stocks they write about or
are paid for their work by a company’s investment department
1. not only investigate, but also if disputes = not only verb, but also conditional clause. We can see that these two are not parallel.
2. “or are paid” makes the sentence further unreadable because a reader may relate “are” to another plural noun “disputes”. Since “or” is parallel marker, it can grammatically make “are” to “result”. This is not the intended meaning though.
D. not only to investigate whether or not research is an independent function at brokerage firms, but also
whether conflicts result when analysts own the stocks they write about or
are1. not only infinitive, but also noun clause – is not parallel at all.
2. “whether or not” – is a redundant construction in this choice because “not” can be omitted but easily discerned by the reader.
3. “or are paid” makes the sentence further unreadable because a reader may relate “are” to another plural noun “disputes”. Since “or” is parallel marker, it can grammatically make “are” to “result”. This is not the intended meaning though.
E. not only to investigate whether research is an independent function at brokerage firms,
or whether conflicts result when analysts own the stocks they write about or
when 1. we have the first halve of the idiom but the other half is missing.
2. “when paid for their work” part misses a verb and thus is a fragment.
Hence
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