A. is the correct answer here.

"Using a formula to supply a default value is a clever way to help your sales rep, but it does have a big limitation. Formula fields can only return certain data types. Since the data type of the Default Field must match the data type of the Target Field, this makes it impossible to use formulas to default certain configuration attributes, such as text areas, picklists, and email addresses.

If you want to supply a default for a field, such as an email address, you have to go about it a slightly different way. Create a normal email field on the Quote object. Then, use something like Flow Builder to populate the field however you want. From that point you can follow the same last eight steps from above, but with your email field API name instead of EngravingDefault__c." - https://trailhead.salesforce.com/content/learn/projects/personalize-smartwatches-with-salesforce-cpq-attributes/set-a-default-value-for-an-engraving-attribute

If it was not a 'dynamic value', the correct answer would be C. But for this requirement, you should populate the field using an automation process (like flows) and then pass it to the configuration attribute.

So, the correct answer is again A....

Given that global attributes in Salesforce CPQ do not work with formula fields, required fields, and hidden or shown picklist values, Option C would not be applicable. In this context, the correct approach to ensure a dynamic default value for a Configuration Attribute would be:

D. Create a Price Rule to target the Product Option field that is used for Configuration Attribute to give it a value. Ensure the end user selects Apply Rules in the Configurator.

C is correct

WHY NOT C ?