You didn't post any option, but the ration roots theorem states that all possible rational roots of a polynomial come in the form
where p divides the constant term and q divides the leading term of the polynomial. So, in your case, p divides 3 (i.e. it is 1 or 3), and q divides 5 (i.e. it is 1 or 5).
So, the possible roots are
For the record, this parabola has no real roots.