Which of the following elements can't be used to create calculated attributes in an Aggregate?

Which of the following elements can’t be used to create calculated attributes in an Aggregate?

Which of the following elements can’t be used to create calculated attributes in an Aggregate?
A . Variables.
B. Server Actions using Entity Attributes.
C. Built-in Functions that can be translated to SQL (e.g. Length(), Power()).
D. Value of the attributes of the Source Entities.

Answer: B