Suspense account

Hi, this is the question from p.278 in Kaplan's this year's F3 text: The debit side of a company's TB totals $1,200 more than the credit side. Which of the following errors would fully account for the difference? A) The petty cash balance of $1,200 has been omitted from the TB B) A receipt of $1,200 for commission receivable has been omitted from the records C) $600 paid for plant maintenance has been correctly entered into the cash book and credited to the plant cost account D) Discount received of $600 has been debited to the discount allowed account The correct answer is D. A discount received should debit Payables and credit the Discount received account. To fix, one should credit the incorrecly debited Discount allowed with $600 and credit the Discount received account instead. This would increase the credit side of the TB by $1,200. How does the suspense account come in play here (if indeed it does)?