If $I_m$ denotes the set of integers modulo $m$, then the following are fields with respect to the operations of addition modulo $m$ and multiplication modulo $m$ :
- $Z_{23}$
- $Z_{29}$
- $Z_{31}$
- $Z_{33}$
- (i) only
- (i) and (ii) only
- (i), (ii) and (iii) only
- (i), (ii), (iii) and (iv)