in relation to AASB138 Intangible assets, which of the following statements is incorrect?

a. Intangible assets are to be derecognised on disposal

b. Reducing-balance method must be used for an intangible asset with an infinite useful life

c. Gains or losses on disposal are calculated as the difference between the proceeds on disposal and the carrying amount at point of sale, with amortisation calculated up to the point of sale

d. Intangible assets are to be derecognised when there are no expected future benefits from the asset