To answer this question, let's go through each option and understand why it is correct or incorrect:
Option A) A comma has been left after the STATS_EXIST_EXCEPTION exception.
This option is incorrect because there is no comma after the STATS_EXIST_EXCEPTION exception in the given procedure. Therefore, this is not the reason preventing the successful creation of the procedure.
Option B) The STATS_EXIST_EXCEPTION has not been declared as a number.
This option is incorrect because the STATS_EXIST_EXCEPTION is not required to be declared as a number. It is used as an exception in the procedure.
Option C) The STATS_EXIST_EXCEPTION has not been declared as an exception.
This option is correct because the STATS_EXIST_EXCEPTION has not been declared as an exception in the given procedure. In order to use an exception, it needs to be declared beforehand using the EXCEPTION keyword followed by the exception name.
Option D) None
This option is incorrect because, as explained above, the STATS_EXIST_EXCEPTION has not been declared as an exception in the given procedure, which prevents the successful creation of the procedure.
The correct answer is C. The STATS_EXIST_EXCEPTION has not been declared as an exception. This option is correct because the exception needs to be declared before it can be used in the procedure.