A business impact analysis (BIA) is the most useful resource for calculating the exposure factor in a risk assessment. The BIA helps identify the criticality of systems and processes and quantifies the potential financial and operational impact of vulnerabilities being exploited. By understanding the business impact, the security team can more accurately determine the exposure factor, which is the proportion of an asset's value that is at risk in the event of a security incident. CASP+ highlights the role of BIAs in understanding risk exposure and supporting effective risk management decisions. References: * CASP+ CAS-004 Exam Objectives: Domain 1.0 - Risk Management (Business Impact Analysis and Risk Exposure) * CompTIA CASP+ Study Guide: Business Impact Analysis for Risk Assessment