正解:C
The results of the previous audit are an important source of information for an IS auditor to consider when performing the risk assessment prior to an audit engagement, as they can provide insights into the current state and performance of the auditee, identify any issues or gaps that need to be followed up or addressed, and highlight any areas that require special attention or focus. The designof controls is an important factor to evaluate during an audit engagement, but it is not the most important thing to consider when performing the risk assessment prior to an audit engagement, as it does not reflect the actual implementation or effectiveness of the controls. Industry standards and best practices are useful benchmarks or guidelines for an IS auditor to compare or measure against during an audit engagement, but they are not the most important thing to consider when performing the risk assessment prior to an audit engagement, as they may not be applicable or relevant to the specific context or objectives of the auditee. The amount of time since the previous audit is a relevant criterion to determine the frequency or timing of an audit engagement, but it is not the most important thing to consider when performing the risk assessment prior to an audit engagement, as it does not indicate the level or nature of risk associated with the auditee.