What does %d, , %c, %s mean and what's their difference?

Not sure in what environment your asking for, but in C programming, %d is an integer (basically a number), %c is a character, that is a single alphanumeric character, where as %s is a series of alphanumeric characters, in programming %s is actually just an array of characters (so multiple %c), but don't worry about that to much. 

Examples in c. 

int number = 1;
char character = "c"; (numbers (integers) can be characters)
char string[5] = "abcd"; ([5] implies 5 characters, here there are 4, that is because an invisible character exists known as a "null terminator" (\0).

The correct answer to this question is :

%d %c and %s are data specifiers used in C programming. It specifies what data type that is being used in order to input and/or output the exact thing that you expected.

%d is for integers
%c is for single character
%s is for strings.

Idon’t know this one

The one that’s keeps you out of legal trouble