Insufficient data for precise adjustment calculation Steps:

• Identify specific irrecoverable debt: $400 to be written off, reducing trade receivables to$28,000 - $400 =$27,600.
• Calculate required provision: 5% × $27,600 =$1,380.
• Compare to existing provision balance: $1,380 -$120 = $1,260 increase needed.
• Entry: Credit provision for doubtful debts $1,260 (but options do not match, indicating ambiguity in whether write-off affects receivables base for 5% or if "all receivables" equals "trade receivables").

Not enough information.

Final answer: A