Anomers are cyclic monosaccharides that differ in configuration only at the acetal or hemiacetal carbon or at the anomeric carbon atoms.

The cyclic monosaccharides given in option (iii) differ in configuration only at C1 carbon atoms. Thus, option (iii) is correct.

Options (i) and (ii) are incorrect because the pairs of monosaccharides given in these options are not a cyclic monosaccharides.

Option (iv) is incorrect because they are enantiomers, i.e., mirror image of one another.