Answer the following questions about decimal expansions of rational numbers.
a. (i) Define a rational number.
b. (ii) State the condition, in terms of the prime factors of the denominator, under which the decimal expansion of a rational number terminates.
c. (iii) Without actually performing long division, decide whether the decimal expansion of each of the following fractions terminates or is non-terminating recurring. Give a brief reason for each answer.
(A) 3213
(B) 4529
(C) 12521