Explanation:

Correct Answer is (c).The statement talks about an Independent Judiciary being one of the major strengths of India’s federal structure and that it has played an important role in strengthening federalism in India.
The original statement is incorrect as it seems to imply that the judiciary has not started to play a role in strengthening federalism and does not match with the tense of the rest of the statement.
Option A is incorrect due to subject-verb agreement rules. The subject here (judiciary) is singular and thus needs a singular verb. Thus, the correct form of play would be plays here.
Option B is clearly absurd in terms of the sentence structure and does not make sense.
Option D is incorrect as the statement is in the past tense indicating the judiciary no longer plays this role. Also, the sentence structure does not make this fragment a good fit in the original sentence.
Option C is correct grammatically and contextually.Hence, option C is correct.