The correct answer is: B. Rs. 50,000
As per Section 47 of the Information Technology Act 2000, any person who fails to maintain books of account or other documents as required under any law for the time being in force shall be punishable with imprisonment for a term which may extend to one year, or with fine which may extend to fifty thousand rupees, or with both.
Option A is incorrect because the maximum penalty for failing to maintain books of account is Rs. 50,000, not Rs. 5,000.
Option C is incorrect because the maximum penalty for failing to maintain books of account is Rs. 50,000, not Rs. 25,000.
Option D is incorrect because the maximum penalty for failing to maintain books of account is Rs. 50,000, not Rs. 1,50,000.