The formation of pyranose and furanose forms of sugar generates a new asymmetric carbon, giving rise to α- and β‑forms. If the resulting anomeric alcohol group is above the plane of the sugar, the structure is known as

a. the D‑enantiomer.
b. the epimeric stereoisomer.
c. the β‑anomer.
d. the α‑anomer.
e. the L‑enantiomer.