Even though his predilection for initiating legal proceedings against

I missed the intended meaning and choose A ..
After revisiting the sentence , C seems best , contrast is A is not required ...

I am stuck between option A and C, and more of inclined towards A, Can you give your explanation for this question?

I would like to go for A instead of C .

C changes the meaning. A says that the politician's predilection for legal action is basically a common knowledge for all and it is unlikely to upset his supporters.
But in C says that the politician inclines to initiate legal action without the common knowledge of his detractors .That is totally different meaning and we should not go for the alternate meaning unless it is the only logical option.

But I think the question could have been written in a better way.There is no need to use the contrast even though in option A.

You'll have to be slightly careful about "changes the meaning". Generally, you should read the sentence and all the 5 options. Then you should ask yourself what the correct meaning should be. That is, don't assume that A will always communicate the right meaning.

Grammatically, one doubt about the correct choice C is whether it displays correct parallelism around the conjunction ' and' with a noun on one side and another infinitive phrase on the other.

Logically, the irony of his own supporters being unlikely to be upset about his penchant for the legal action raises doubts whether they are his supporters at all.

Structurally, is there anything amiss in the introductory modifier in C? There is a noun 'predilection' in the main modifier and another noun 'common knowledge' standing aloof and nested with it.

The elements joined by the and may not appear parallel, but they are. It may be that we are not applying parallelism the same way. For example, would you consider the following not parallel?

... the fight, each of the last three rounds five minutes long and requiring more energy than either fighter appeared to have.

The explanation given by chetan2u is correct: we do not want the contrast that the even though in option A introduces.

Even though pursuing the case in court had no disadvantages, he pursued the case in court.

This meaning is unexpected, as we would expect someone to pursue a case in court because of [NO DISADVANTAGES], not despite [NO DISADVANTAGES].

Would you pl. confirm whether your quote is from a GMAT context? If it is from any other source, then you may appreciate the futility of discussing it here, as we have seen often that other contexts including from those of top journals and magazines may be wide off from GMAT traditions.

However, if they were parallel, would you kindly define that parallelism, such as whether it is verb parallelism, or infinitive parallelism or noun parallelism or prepositional parallelism or adverbial or adjectival parallelism? Parallelism in GMAT is required to be structurally parallel too.

Any comments with regard to other queries in my post, please.

It's not. I came up with that sentence while typing out my reply. Are you saying that the sentence is parallel (but not parallel enough) for the GMAT or that it is not parallel at all?

As for your other query, it's the same thing: why would you say that putting two nouns together leads to a structural error? As in, where are you coming from on this?

If it is not a GMAT quote but your personal one, IMO, they are not parallel. As also in other points raised by me,
it is seen that the two nouns stated are not even separated by a punctuation mark. If such constructions are your own personal styles, you are entitled to them, as much as one need not entertain them. Best of luck

That is again incorrect. A punctuation mark is the last thing that option needs in between those two nouns. However, I agree that it is best to end this particular discussion here.

(C) His predilection for initiating legal proceedings against his detractors common knowledge and unlikely to upset his supporter

That is the crux. I hope it is not difficult to see that the option is missing the all important article between the nouns. If the author thinks it is ok to drop the article, he is welcome

Please do not bring this completely new point about articles up as a personal style call. It is not. It is indisputably incorrect to put an a before common knowledge. If we try to do what you are suggesting, we get:

His predilection for initiating legal proceedings against his detractors a common knowledge

Putting an a before common knowledge makes the construction incorrect.

B is out b/c of "which" and D is bad b/c of its structure.
THis is not a contrasting relation, so A is out.
E is wrong because this is not a causal relation either, C is absolute phrase

Thank you for the additional examples your provided. They make sense to me, contrary to this question's OA.
I must say I still can't see how answer choice C (below) can ever be correct. Nevertheless, I'm not a 51-verbal scorer.

(C) His predilection for initiating legal proceedings against his detractors common knowledge and unlikely to upset his supporters the politician decided to press charges against his opponent.

I've seen a lot of instructors tell their students that the concepts tested in the verbal section are as clear-cut and consistent as those tested in (let's say) the quant section. But while I think that the best instructors will not try to hide the possible complexity of the verbal section from their students, my 51 should not be the reason you decide to let this go.

There are two (slightly uncomfortable?) concepts tested in C: (a) less than absolutely straightforward parallelism and (b) the usage of a rarely tested modifier. But if option C is fundamentally possible, there is no reason not to mark it, given that the other options are just not viable. And although I don't think the GMAT regularly combines the two ("tough" parallelism and a "tough" modifier), make no mistake about it, the GMAT has tested both multiple times (separately).

If you're open to more examples, you could consider these, again from The New York Times:

Or Sabathia, 37, approximately 300 pounds, working on a bad knee and unlikely to be a Yankee after this season ends. [5]

Most people assumed the attack was an aberration committed by political extremists and unlikely to be repeated. [6]

The rifle association opposes licensing and registration, saying they are undue burdens on law-abiding citizens and unlikely to affect the criminals with guns. [7]

These might sound a little "off", but that doesn't mean that they are wrong. If you combine what these options do with the other examples (the ones you were comfortable with), you will get something similar to option C.

To other readers who may be looking for "GMAT examples" for option C: instructors and test prep companies have a choice. They can invest (a lot of) time and effort in creating new content, or they can (very cheaply and quickly) just reword existing GMAT questions. The second strategy actively hurts students, as a lot of their official practice material becomes less useful (this also explains GMATPrep score inflation to a certain extent). This is why I cannot provide you examples from past GMAT questions that precisely match option C.

On the other hand, if you wish to try more of these questions, you could take a look at these: Formulating a precise search query, Pokémon Go, and Industry representatives.

This question wants to test the absolute phrase.
Do you think this question is a gmat-like in an actual exam? It is because the source if self-made.