which comes under unformatted I/O function?Optionsgets()scanf()sscanf()sprintf()

The unformatted I/O function in this list is gets().

Explanation: Unformatted I/O functions do not require any format specifiers. They read or write characters as they are, without any conversion. In this list, gets() is an unformatted I/O function because it reads a string from the standard input (the keyboard) until a newline character is encountered or end of file is reached.

On the other hand, scanf(), sscanf(), and sprintf() are formatted I/O functions. They require format specifiers to convert the input/output. For example, scanf() reads input from the standard input according to a format, sscanf() reads input from a string according to a format, and sprintf() writes formatted output to a string.