Final answer:
The correct approach is to sync the contact and custom objects with Data Stream in Salesforce, and perform sends from Synchronized Data Extensions, ensuring all data relationships are properly configured with lookup relationships to contact or lead records.
Step-by-step explanation:
To successfully use Salesforce custom object data for segmenting and personalization within the Marketing Cloud (MC), the consultant should take the following approach: Sync the contact and custom objects by using the Marketing Cloud Connect integration with Data Stream and perform the sends from Synchronized Data Extensions.
It is essential to confirm that there is a lookup relationship between the custom object records and a contact or lead record to ensure proper segmentation and personalization. With this setup, data flows automatically and continuously from Sales Cloud into Marketing Cloud, enabling real-time marketing initiatives. When sending an email, you can leverage the data directly from the Synchronized Data Extension.
Aside from ensuring that Salesforce data is correctly synchronized, it's also crucial to maintain data hygiene and compliance with data protection regulations when using customer data for marketing purposes. Thus, the option B from the given choices is the suggested approach for a consultant to meet the requirement.