The correct answer to the question “Which of the following is not used in C language” is option (d). A Word. Because the rest of the options are used in C Language, like, digit, integer, and characters. If you wish to know more about C, check out the C Programming tutorial, and if you want to get certified in C, then enroll in C Language online course. Wish to get started in C, watch the following video on Learn C Programming from domain-experts.