True or False: A resource profile defines where extensions are required or expected.

• A. Not applicable
• B. Sometimes
• C. True
• D. False

Answer: (C)

In FHIR, a resource profile constrains a resource and can specify constraints on extensions, including whether an extension must be present. This is done by setting the min cardinality on the extension element along its path; a minimum of 1 makes the extension required for any instance that conforms to the profile, while a minimum of 0 makes it optional. By defining these constraints, the profile communicates exactly where extensions are required or expected within the resource. So the statement is true.