What is “a” in the given C code?

[answerhappygod]

size_t wcstombs(char *s, const wchar_t *a, size_t n)
a) “a” is wide character string to be converted
b) “a” is pointer to an array of char elements
c) “a” is pointer to the first byte of a multi-byte character
d) “a” C multibyte character string to be interpreted