From your "candidate" answers, I suspect that "heap" is a mistranslation and that you are asking for the "range" of f(x)= 5 cos(x)+ 3. Since the range of cos(x) itself is -1 to 1, 5 cos(x)+ 3 can be any number from -5+ 3= -2 to 5+ 3= 8.
(If, in fact, you meant "domain", that is, of course, all real numbers.)