In which of the following sets can each
number only be classified as rational?
A {0, - 18 , 124, -3, 3)
B {3.5, -4, 23.8, -1.2, 0}
C {-5, 13, 233, 42,3)
D {-7.75, -5.8, 0.125, 4, 21}