Trial balance detects only errors causing unequal debits and credits

Steps:

• Trial balance totals all debit and credit ledger balances to check equality.
• Errors affecting one side more than the other create imbalance and are detected.
• Balanced errors, like equal mispostings on both sides, go undetected.
• Evaluate each option for impact on debit-credit equality.

Why B is correct:

• Duplicating the $950 purchase as two$590 entries totals $1,180 debited to purchases and credited to payables, matching on both sides per the double-entry rule, so trial balance balances despite the error.

Why the others are wrong:

• A: Posting the $850 contra entry (e.g., cash to bank transfer) twice doubles both debit and credit equally, but if only one ledger side is duplicated, it imbalances totals.
• C: Posting $75 to carriage inwards instead of$57 creates an $18 excess debit without matching credit adjustment, unbalancing trial balance.
• D: Crediting discount allowed ($35debitexpense)todi$70 net imbalance.

Final answer: B