To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) A REXX clause can be coded in uppercase, lowercase, or mixed case. - This option is correct. In REXX, you can write code in uppercase, lowercase, or mixed case. The language is case-insensitive.
Option B) Multiple instructions can be coded on 1 line, as long as they are separated by a ',' - This option is incorrect. In REXX, multiple instructions cannot be coded on a single line by separating them with a ','. Each instruction should be written on a separate line.
Option C) A REXX program should start with a comment clause /* REXX / - This option is correct. It is a good practice to start a REXX program with a comment clause / REXX */ to indicate that it is a REXX program.
Option D) Continuation of REXX instructions is achieved by using a ',' as a continuation indicator - This option is correct. In REXX, you can use a ',' as a continuation indicator to continue a statement onto the next line.
The correct answer is B. Multiple instructions cannot be coded on 1 line, as long as they are separated by a ','. This statement is not correct in a REXX program.