Answer
(a) no match.
(b) no match.
(c) match (i)
(c) match (iii)
Work Step by Step
(a) We have two different bases and can not put them together. Thus, there is no match.
(b) Since $\frac{2^a}{3^{b}}=2^a3^{-b}$, then for (b) there is no match.
(c) We can multiply the exponents to match (i).
(d) Note that $b-a=-(a-b)$
Thus we have: $2^{a-b}3^{-(a-b)}$, which matches (iii).
