What should you search for and if necessary replace in the existing custom ABAP code?

One of your SAP systems needs to be migrated from its current database to an SAP HANA database. You want to avoid any functional issues after the migration.

What should you search for and if necessary replace in the existing custom ABAP code? There are 3 correct answers to this question.
A . Direct access to a cluster on the database
B . Left outer joins in open SQL statements
C . Native SQL statements
D . Code that relies on implicit database sorting
E . ORDER BY Clauses in Open SQL statements

Answer: A,C,D