The correct answer is A. We practiced for the debate and many arguments were rehearsed.
As you can see in this sentence, in the first part the pronoun <em>we </em>is used, and in the latter part, that pronoun just disappears and the sentence suddenly becomes passive rather than active. The shift isn't done properly - it is rather awkward. The other options are consistent - they use only one voice rather than two (like in sentence A).
Chandigarh is 
capital of Punjab.
Answer:
a topic sentence
an approach that uses passive voice
an explanation of the target audience and the technique used
specific details from the posters
The other option of the answer
