A,C,D are the right ones. https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_exception_custom.htm

'Exceptions can be top-level classes, that is, they can have member variables, methods and constructors, they can implement interfaces, and so on.'
'To create your custom exception class, extend the built-in Exception class and make sure your class name ends with the word Exception'
'All exception classes extend the system-defined base class Exception'

I believe that A, C, D are the correct answers