Explanation:

Correct answer is (b). The bold part of the sentence has an error and that is why there should be replacement of the bold part of the statement. Here, the problem is with the appropriate preposition used with take. Take of is not the correct usage in this context as we imply that Sudipta is going to take the responsibility for something. Take over is actually used for that purpose.
The correct sentence would be: As per the results of the by-election, Sudipta is going to take over as the chairman of the committee formed by the government from the next month. This makes option B the correct choice among the given options.