Final answer:
Only the second scenario, where £100 could not be reconciled and was posted to a suspense account, would on its own cause a debit balance of £100 on the suspense account. The misallocated telephone bill affects only the relevant expense accounts and not the suspense account.
Step-by-step explanation:
Regarding the inquiry on which of the following would, on their own, be the cause of a debit balance of £100 on the suspense account, we must look at the two scenarios provided. First, a £100 telephone bill being debited to the electricity account would not cause a debit balance in the suspense account; it merely represents misallocation between expense accounts. Therefore, the telephone bill scenario does not apply.
Secondly, if the exception report showed £100 paid from the business bank account that could not be matched by the accounting system and therefore had been posted to a suspense account, this directly affects the suspense account balance. Since the £100 was debited to the suspense account due to it not being reconcilable at the time, this scenario would result in a debit balance of £100 in the suspense account. No offsetting credit entry has been made to balance it, hence the existence of the debit balance.