D is the answer to this question. CNC programming is also known as Computer Numerical Control Programming. This is something that is used by various manufacturers in order to create program instructions that can be used to place in computers.
If the computers will not be programmed properly, they will not work according to how you have planned. It is important to understand the basics of this program so that you can create the right program according to what you need. There are some tutorials online that will teach you what to do. Some would take courses in order to know how to do this properly.