C.
Explanation:
Natural language processing or NLP can be defined as an artificial intelligence that aids computers to understand, interpret, and manipulate human language. NLP is subfiled of many disciplines, for instance, artifical intelligence, linguistics, computer science, etc. NLP helps computers to interact with humans in their own language.
So, the easier way through which people can communicate with computers apart from GUI is NLP. Thus option C is correct.
i am not but thanks for the points