During the initial phases of any audit engagement, it is customary for the auditor to spend time attempting to gain an understanding of the client and the industry in which the client operates. This phase of the audit is best described as the controls testing phase, characterized by the auditor gaining an understanding of which controls are typically tested in the client's industry. the initial audit planning stage, characterized by understanding key features of the client and the industry such as transactions and balances. O the audit planning stage, characterized by performing tests of controls to determine an appropriate audit strategy for the client. O the substantive planning stage, characterized by the undertaking of preliminary audit strategies such as issuance of an initial audit opinion