How are you, my friend? Once again, these are astute questions, and I am happy to respond.
While (B) has other problems, the structure about which you ask is 100% correct without the word " on
." The structure is . . . to have as my X Y . . .
, the object of the preposition " as
," indicates a role or function, and Y
is the person or thing that fulfills that role or function. The verb could also be "hold" or some related verb of possession. I have as my friend the police chief in town.
I have as my primary mode of transportation a mountain bike.
I hold as my ideal the teachings of Zen.
I treasure as my favorite movie Casablanca .
I have as a question in my mind whether zoezhuyan will understand my explanation.
In the last example, the Y
is not a simple noun but a substantive clause , a full clause that takes the role of a noun. That's precisely what is happening in (B). The X
is the word " focus
" and the Y
is a substantive clause. This is perfectly correct.
Now, about the parallelism in (C)--remember, first of all, that parallelism is not a grammatical structure, but a logical structure, and the grammar simply follows the logic and supports it. Think about "question clauses"--these are substantive clauses that represent the indirect statement of a question. My question is what the right answer might be.
My question is what his name is.
My question is whether it will rain.
My question is how fall she can throw a baseball.
My question is to whom should I make the check payable.
My question is for whom was the symphony written.
My question is against whom is he arguing.
My question is in what does she really believe?
The words " who
" and " what
" serve as relative pronouns. They open subordinate clauses, in these causes substantive clause that are acting as nouns. Like all pronouns, relative pronouns can be the object of a preposition, even when they open a subordinate clause.
Notice, incidentally, in American colloquial English, many speakers will avoid these sophisticated constructions by ending the sentence with a preposition. My question is whom should I make the check payable to.
My question is whom was the symphony written for.
My question is whom is he arguing against.
My question is what does she really believe in?
In the big world of grammar, this is controversial issue. Many intelligent people would say that it's perfectly fine to end a sentence with a preposition: these people are taking a more grammatically liberal position. Others, such as I, are grammatically conservative and are appalled but such structures. That's the spectrum in the big world of grammar. Now, in the much more limited world of the GMAT, the GMAT SC tends to be quite conservative grammatically. I have never seen an official prompt whose OA had a sentence or clause ending in a preposition; this questionable structure appears rarely, and only on incorrect answer choices--that is, choices that are clearly incorrect for other reasons. The GMAT seems to disapprove of this structure but never tests is directly.
Thus, from the information in (C), we could say: Discussion of greenhouse effects has usually focused on whether Earth would grow warmer.
Discussion of greenhouse effects has usually focused on to what extent Earth would grow warmer.
Each one of those sentences is correct on its own, and it sounds clumsy and redundant to state them separately in a side-by-side way like this. What (C) has is an exceptionally sleek and elegant combination. Logically, these are both questions, so the parallelism between them is perfect.
Does all this make sense?
Have a wonderful day, my friend.