IFRS permits companies to carry assets at historical cost or use a revaluation model for fixed assets. According to IAS 16, if revaluation is used: 

1. it must be applied to all assets in a class of assets.

2. assets must be revalued on an annual basis.

3. assets must be depreciated on the straight-line basis.

4. salvage values must be zero.

Which of these answers is correct, it can be multiple choices