Which of the following instructions would be used to perform multiplication in a programmable controller?

The instruction used to perform multiplication in a programmable controller is represented by the code "MUL." This is specifically designed for carrying out multiplication operations within the programming of a controller. When you use the MUL instruction, it takes two input values and calculates their product, which can then be stored or used for further processing in the control logic.

In programmable logic controller (PLC) programming, having specific instructions like MUL allows for clear and efficient operation definitions. Each instruction is optimized for a certain type of arithmetic or data manipulation, making it easier for programmers to read and understand the code.

The other options serve different functions. For instance, MOV is used for moving data from one location to another, ADD is for summing values, and SUB is for subtraction. Each of these instructions has its unique purpose, which is distinct from that of the multiplication instruction. Thus, understanding the specific functionalities of each command helps in writing effective and correct PLC programs.