Implementing a Master Data Management strategy to reconcile Leads, Accounts, and Contacts is the approach that the architect should suggest so that the requirements are met for UC. A Master Data Management strategy can provide a consistent and unified view of data across multiple systems, by defining and enforcing rules for data quality, governance, and integration. A Master Data Management strategy can also handle complex scenarios where different systems have different systems of record for different entities or fields, and where data can be modified in different systems with different values. A Master Data Management strategy can also provide a consolidated data store that links referenced records across systems and enables cross-system reporting and analysis. The other options are not suitable or sufficient for meeting the requirements, as they would either not provide a consolidated data store, not handle different systems of record, or not allow data modification in different system