Change in accounting policy

Box has used first-in-first-out to measure its inventory for many years. On 1 October 20X4 Box moved to using average cost. This increased the inventory value at that date by $200,000. Which of the following is NOT the correct accounting treatment for the financial statements for the year ending 30 September 20X5? A Increase opening retained earnings in the statement of changes in equity by $200,000 B Increase the prior year comparative statement of financial position inventory by $200,000 C Increase the cost of sales for 20X5 by $200,000 D Decrease the cost of sales for 20X5 by $200,000 Reduce the profits in the prior year comparative statement of profit or loss by $200,000 The correct answer is d In my opinion since the inventory value has increased and it is a case of change in accounting policy, Effect should be taken retrospectively and there for increasing the closing inventory for the year ended 30 September 20X4 And as the closing inventory increases profits also increase Thus most Accurate option according to me is B Thank you in advance :’)