Which of the following is not a valid comment about the use of analytical procedures in the audit of property, plant & equipment (PPE)? Select one: a. compare the annual depreciation charge with the cost of an asset to approximate the depreciation rate. b. a substantial asset balance variation can be caused by one or a few transactions of which the auditor is likely to already be aware. comparison of repairs expense with prior years may indicate capitalization in error. d. none of the above are invalid