Comprehension \( \quad: \) It is convenient at times to represent the cyclic structure of a mono...

Comprehension \( \quad: \) It is convenient at times to represent the cyclic structure of a monosaccharide without specifying whether the configuration of the anomeric carbon atom is \( \alpha \) or \( \beta \). When we do this, we shall use formulas such as the following:
\( w \) Indicates \( \alpha \) or \( \beta \) (three-dimensional view not specified)
The given structure is enol form of
(a) D-glucose
(b) D-mannose
(c) D-fructose
(d) All of these