What instruction will send program flow to a sub-program?

The instruction that sends program flow to a sub-program is the CALL instruction. When this instruction is executed, the main program's execution halts, and control is transferred to the specified sub-program. This allows the sub-program to run its sequence of instructions independently.

Once the sub-program completes its execution, control returns to the point in the main program immediately following the CALL instruction, allowing the overall program flow to resume seamlessly. This structure is essential for organizing code, enabling code reuse, and significantly improving the clarity of programming by breaking large tasks into smaller, manageable sub-tasks.

Other options do not function in the same way as the CALL instruction. GOTO is typically used to transfer control within the same program but does not facilitate the transition to a separate sub-program. EXECUTE, while suggestive of running a program, is not a standard instruction for sub-program transfer in this context. RETURN is used at the end of a sub-program to send control back to the calling program, but it does not initiate the call to the sub-program itself.