Which of the following statements best describes the nature of depreciation? LO9 a Regular reduction of asset value to correspond to changes in market value as the asset ages b A process of correlating the carrying value of an asset with its gradual decline in physical efficiency c Allocation of cost in a manner that will ensure that plant and equipment items are not carried on the balance sheet at amounts in excess of net realizable value d Allocation of the cost of a plant asset to the periods in which services are received from the asset