Making use of a third-party tool to help merge duplicate Contacts across Accounts and using Data.com to standardize Contact address information to help identify duplicates are two solutions that UC should implement to cleanse their data and have a single Contact across departments. A third-party tool, such as an app from the AppExchange, can provide advanced features and capabilities for finding and merging duplicate Contacts across different Accounts, based on various criteria and rules. Data.com can provide address verification and standardization services that can enhance the quality and consistency of Contact address information and make it easier to identify duplicates. The other options are not feasible or effective for cleansing the data, as they would either not work across different Accounts, not address the root cause of duplication, or not provide sufficient functionality for merging duplicates

Implementing a workflow rule that sends Opportunity data through Outbound Messaging is the optimal real- time approach that achieves the solution of copying Opportunity records to the ERP once they reach a Closed
/Won Stage. A workflow rule can trigger an Outbound Message when an Opportunity record meets certain criteria, such as having a Closed/Won Stage. An Outbound Message can send data from Salesforce to an external system via SOAP API, without requiring any code. The external system can then process the data and create a read-only record in the ERP system. The other options are not optimal or real-time, as they would either require additional systems or tools, not provide real-time data synchronization, or not meet the frequency requirement

Removing custom indexes on the data being loaded will prevent unnecessary index maintenance and improve the data load speed. Deferring sharing calculations of the Salesforce Org will avoid frequent sharing rule evaluations and reduce the load time. Deactivating approval processes and workflow rules will prevent triggering any automation logic that might slow down or fail the data load.

According to the Data Modeling unit on Trailhead, some of the key actions that should be done when data modeling in Salesforce are identifying data elements, mapping legacy data, and implementing legacy data model. The unit states that "Before you start creating objects and fields in Salesforce, you need to identify the data elements that you want to store and work with. ... Next, you need to map your legacy data to Salesforce objects and fields. ... Finally, you need to implement your data model in Salesforce by creating custom objects and fields using declarative tools or Metadata API." Therefore, these are the correct actions for migrating a legacy client server app to Salesforce.

A master data management (MDM) strategy for customer data can help UC ensure that all systems have access to the same customer information, without loading or duplicating data in all systems. An MDM strategy can also help UC avoid data conflicts and inconsistencies that may arise from having multiple systems as owners of data.