What can be done to enable the debug information for functions to be displayed when using ‘ksh - x’to debug a script?（）

• A、Run the script using 'ksh -fx'.
• B、Run the script using 'ksh -a function -x'.
• C、Edit the script and add 'set -x' at the beginning.
• D、Edit the script and add 'set -x' at the beginning of each function.