The correct answer is D - Business assets that will be stored in the new system.
As described in WGU Cybersecurity Architecture and Engineering (KFO1 / D488), the first step in risk management is identifying and classifying assets that need protection. Without understanding the business assets, you cannot properly assess threats, vulnerabilities, or impacts.
Threats (A), impacts (B), and vulnerabilities (C) are assessed after assets are identified.
Reference Extract from Study Guide:
"Identifying and classifying business assets is the first step in the risk management process, as assets drive the prioritization of threats and mitigations."
- WGU Cybersecurity Architecture and Engineering (KFO1 / D488), Risk Identification and Asset Classification