The pentaacetate of glucose does not react with hydroxylamine. This indicates that the aldehyde in glucose is not free and is involved in the formation of cyclic structure. Hence, this reaction of glucose can only be explained by its cyclic structure. Thus, option (iii) is correct.

Option (i) is incorrect because the capability of glucose to form pentaacetate tells us about the 5 hydroxyl group of the glucose.

Option (ii) is incorrect because this reaction confirms the presence of a carbonyl group in glucose.

Option (iv) is incorrect because this reaction indicates the presence of a primary alcohol in the glucose.