Relationship of Discriminant in Quadratics

Consider the quadratic expression:

$$f(x) = ax^2 + bx + c$$

where $$a$$, $$b$$, and $$c$$ are real numbers and $$a \neq 0$$. If the roots of this quadratic equation are real and distinct, which of the following statements is true about the discriminant $$D$$ of the quadratic equation? The discriminant is given by $$D = b^2 - 4ac$$.