C: True. In Oracle Database 12c, character sorts are case-sensitive by default, meaning that it differentiates between uppercase and lowercase letters when sorting data. This behavior aligns with the binary collation rules typically used, unless explicitly overridden by using different collation settings.
D: True. Column aliases can indeed be used in the ORDER BY clause in Oracle SQL. This allows for more readable and maintainable code, as you can define a column alias in the SELECT list and refer to that alias in the ORDER BY clause. This usage promotes clarity, especially when dealing with complex calculations or function applications in the select list.