Answer :
If x=3 is a point of discontinuity of f(x), then, it must be true that h(3) is 0 or is the root of a negative value. This is because for a value to be a point of discontinuity, it must indefine the function. That is why there are 2 options, h(3)=0, that indefines the function because you can not divide a number by 0; or h(3) is a negative root, that indefines the function because negative roots are imaginary.