Unit tests in Salesforce are designed to test Apex code functionality and can execute certain operations within the testing context.
Option C: Generate a Visualforce PDF with getContentAsPDF
Reference:
"The getContent and getContentAsPDF PageReference methods can be used in test methods."
- Apex Developer Guide: Testing GET and POST Methods
Why Other Options Are Incorrect:
Option A: Load data from a remote site with a callout
Callouts to external services are not allowed in unit tests unless you use a mock callout framework.
"Test methods can't make callouts to external systems. To test callouts, use mock callouts by either implementing an interface or using static resources."
- Apex Developer Guide: Testing HTTP Callouts
Option B: Execute anonymous Apex as a different user
Executing anonymous Apex isn't possible within a test method, and you can't change the user context arbitrarily in tests except with System.runAs, which doesn't execute as a different user for anonymous code.
"You can use System.runAs to run code as a different user, but you cannot execute anonymous Apex in this way within a test."
- Apex Developer Guide: Running Apex as Another User
Option D: Set the created date of a record using a system method
System fields like CreatedDate are not writeable in Apex tests.
"You can't set values for fields that have the Createable attribute set to false, such as system fields like CreatedDate or LastModifiedDate."
- Apex Developer Guide: DML Statements