The correct answer is: A. 10 May and 15 July
The Lok Sabha Election 2004 was held on 10 May 2004. However, the voting in Chhapra constituency in Bihar was cancelled due to violence and re-polling was held on 15 July 2004.
Option B is incorrect because the voting in Chhapra constituency was cancelled on 10 May 2004, not on 31 May 2004.
Option C is incorrect because the voting in Chhapra constituency was cancelled on 10 May 2004, not on 15 May 2004.
Option D is incorrect because the voting in Chhapra constituency was cancelled on 10 May 2004, not on 25 May 2004.