Concept:QBASIC has a fixed set of reserved keywords; FIND is not one of them.
Explanation:LET, REM, and STOP are all valid QBASIC keywords.
LET is used to assign a value to a variable.
REM is used to add a comment or remark in a program.
STOP is used to halt program execution.
However, FIND is not a keyword in QBASIC.
Therefore, the option that is not a QBASIC keyword is FIND.
Answer:A. FIND