The correct answer is: (ii), (iii) and (iv)

Statement (i) is not correct. A debit to stores with a corresponding credit to work in progress (WIP) indicates that direct materials returned from production were $18,000.

Statement (ii) is correct. Direct costs of production are 'collected' in the WIP account.

Statement (iii) is correct. Indirect costs of production or overhead are 'collected' in the overhead control account.

Statement (iv) is correct. The purchases of materials on credit are credited to the creditors account and debited to the material stores control account.

Therefore the correct answer is (ii), (iii) and (iv).