#### Answer

(a) $100$
(b) $0, 100, -8$
(c) $-1.5, 0, 5/2, 2.71, 3.1\bar4, 100, -8$
(d) $\sqrt7, -\pi$

#### Work Step by Step

(a) Natural numbers are positive integers, so only 100 qualifies.
(b) Integers are positive or negative whole numbers and zero, so 0, 100, and -8 qualify.
(c) Rational numbers are those that can be expressed as a ratio of integers.
-1.5=-3/2, so it qualifies.
0=0/1, so it qualifies.
5/2 is a ratio of integers, so it qualifies.
2.71=271/100, so it qualifies.
$3.1\bar4$=283/90, so it qualifies.
100=100/1, so it qualifies.
-8=-8/1, so it qualifies.
(d) Irrational numbers can not be expressed as ratios of integers, so $\sqrt7$ and -$\pi$ qualify.