Consider the following statements:

1. $a^0 = 1$ for $a \neq 0$
2. $a^{-n} = \dfrac{1}{a^n}$ for $a\mathrm{\ne }0,$
3. $(ab)^n = a^n b^n$ for $a, b \in R,\, n \in N$

• ai and ii
• bii and iii
• ci and iii
• di, ii and iii