The function ____ returns a non-0 number if the argument is a letter or a digit; otherwise it returns a 0.

A) int isalnum(int)
B) int isalpha(int)
C) int isdigit(int)
D) int isxdigit(int)

Isalnum

A function in C that checks if a given character is an alphanumeric character (either a letter or a number).

Non-0 Number

A numeric value different from zero, indicating either a positive or negative value but not the absence of a quantity.