A Real-time CDP business practitioner wants to fetch merged profile data of a customer across...

According to the Adobe documentation3, identity value and namespace are two elements that must match in the data sources for the profile to merge. Identity value is the unique identifier for a customer, such as an email address or a phone number. Namespace is the type or source of the identity value, such as Email or Phone Number. When two data sources have the same identity value and namespace, they can be stitched together to form a unified profile.References: 3 https://experienceleague.adobe.com/docs/experience-platform/profile/identity-service/overview.html?lang=en#identity-service-overview