Carbohydrates are classified as monosaccharides, oligosaccharides and polysaccharides depending on their behaviour towards hydrolysis. All monosaccharides containing five or six carbon atoms can have two cyclic structures namely furanose and pyranose form. Oligosaccharides are further classified as di, tri, tetra etc saccharides depeding upon the number of monosaccharide units actually obntained on hyrolysis. In oligosaccharides and polysaccharides, the different monomer units are joined together by glycosidic linkages. Mutarotation involves (a) conformational inversion (b) racemisation (c) diastereoisomerisation (d) epimerization

Mutarotation is the change in the optical rotation of a compound, specifically a carbohydrate, when its structure interconverts between different anomers (α and β forms). This process involves the opening of the cyclic structure, creating an equilibrium between the two alternative forms. The phenomenon of mutarotation is unique to carbohydrates and is observed when carbohydrates change between the α and β anomer forms.

We have four options to consider in terms of mutarotation: (a) conformational inversion (b) racemisation (c) diastereoisomerisation (d) epimerization We need to choose which one of these describes the mutarotation process.

(a) Conformational inversion: This is a change in an object's spatial arrangement, but in this case, it does not adequately describe mutarotation as it does not involve changing between the α and β forms. (b) Racemisation: This is the process of converting a single enantiomer into a racemic mixture (equal amounts of two enantiomers). However, mutarotation does not involve converting a specific enantiomer to a racemic mixture; instead, it involves interconversion between two anomers. (c) Diastereoisomerisation: This is the process of converting one diastereoisomer into another. Since anomers are diastereoisomers, mutarotation is a specific type of diastereoisomerisation. This option is a more accurate description of mutarotation. (d) Epimerization: This is the process of converting one epimer into another. Although this process involves changes in carbohydrates structure, it doesn't relate directly to the conversion between α and β anomers, which is the central aspect of mutarotation.

After analyzing the given options, we can conclude that the phenomenon of mutarotation involves diastereoisomerisation (c).