D is the answer to this question. Are you familiar with what an algorithm is? This is the process by which there is a specification on how the programs and problems can be solved. There are different algorithms that can be performed by human beings but it is more likely that the algorithms will be performed by different machines.
Aside from calculation, algorithms are also known to be effective in processing different types of data, automated reasoning, and a lot of other tasks that are available. There are times when the algorithm will be in charge of making some processes clearer. Some machines are not meant to solve vague instructions that may come from people.