Three cyclic structures of monosaccharides are given below which of these are anomers.

(I)

(II)

(III)

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 I and II differ in configuration only at C1 atom. Therefore, they are anomers. Thus, option (i) is correct.

Options (ii) and (iii) are incorrect because the numbers of carbon atoms in both the cyclic compounds in each of the options are different. They differ from each other at C1 position Thus, they are not anomers.

Option (iv) is incorrect because III is not an anomer of I and II. They differ in the number of carbon atoms and they differ from each other at C1 position.