int printf ( const char * format, ... );
They were probably asking this to see if you were familiar with the optional parameter syntax "...". This allows you to pass an indeterminate list of variables that will fill in the format string.
For example, the same method can be used to print things like this:
printf("This is a string: %s", myString);
printf("This is a string: %s and an int: %d", myString, myInt);
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