Correct Answer is A. Access Control Rules

Here's why:
Access Control Rules specifically control who can access what data or files, within or across scopes.
They’re evaluated every time someone tries to read, write, create, or delete data.

Meanwhile:
Application Scope is more about application-level isolation, like preventing another app from modifying your scripts or tables unless granted access.

So, to summarize:
D (Application Scope) helps protect the application itself from interference.
A (Access Control Rules) protect the data and files within the app.