$9-10=$ Real Numbers List the elements of the given set that are
$$\begin{array}{l}{\text { (a) natural numbers }} \\ {\text { (b) integers }} \\ {\text { (c) rational numbers }} \\ {\text { (d) irrational numbers }}\end{array}$$
9. $\left\{-1.5,0, \frac{5}{2}, \sqrt{7}, 2.71,-\pi, 3.1 \overline{4}, 100,-8\right\}$