Answer:
b) A decrease in ownership percentage from 25% to 15%
Explanation:
There is change in accounting method when the shareholding is 20% or more.
Under Consolidation there are two methods:
Equity method: This is used when the shareholding is 20% or more, and there is significant influence. Under this method all the assets and liabilities are accumulated in the consolidated balance sheet.
Proportional Consolidation method: This is generally used when the shareholding is merely shown as an investment, and the balances of assets and liabilities are not accumulated.
Thus, there is a change in method of accounting when the shareholding is more than 20%. This is in case b as change is from 25% to 15% and thus, it will change from equity method to proportional consolidation method.