Which two statements are true about REF CURSOR types?

Which two statements are true about REF CURSOR types? (Choose two.)

A.
REF CURSOR types cannot be defined inside a package.

B.
SYS_REFCURSOR can be used to declare cursor variables in stored procedures and functions.

C.
A REF CURSOR return type can be declared using %TYPE, or %ROWTYPE, or a userdefined record.

D.
Only a weak REF CURSOR type can be used as a formal parameter of a stored procedure or function.