Exam Certified Marketing Cloud Consultant topic 1 question 39 discussion

each contact has its demographic info such as age, race, marital status, etc. This should be mapped to each contact on 1 to 1 basis

Agreed I think the answer is D From Salesforce documentation "A 1:1 relationship indicates that the data extensions relate to each other on a single piece of information called a primary key. You can use a membership ID number or a mobile phone number as a primary key, among other values. Each data extension contains a single reference to that primary key. 1:1 relationships act as an extension of contact record attributes, such as demographic information from an outside source linked via an email address or mobile number."

This is very subjective. Of course each individual should have their own combination of demographic information such as age, race, ethnicity, gender, marital status, income, education, and employment. Generally we can segment based on matching information between subscribers. The only way in which this is a one to many relationship is if the demographic information falls into a range, for example Age field (bellow 18, between 18-25, between 26-25 and so) Otherwise I agree it should be D.

1 to 1 basis is needed for the relationship, otherwise as GTSalesforce said correctly, so D is correct.

the answer is definitely D