Dynamic Rule-Based Insurance Underwriting Engine

Design an underwriting engine where insurance agents can define complex rules to determine if a policy application is approved, denied, or requires manual review. Rules are based on applicant data (age, medical history, location) and can be nested (e.g., 'If (A and B) or C'). The system must support 'versioning' so that an application submitted today is evaluated against today's rules, even if the rules are updated tomorrow. It must also allow for 'what-if' simulations.