In cyclic structure of maltose, acetal bond is formed between
A. C-2 of one glucopyranose and C-2 of another glucopyranose
B. C-1 of one glucopyranose and C-2 of another glucopyranose
C. C-1 of one glucopyranose and C-4 of another glucopyranose
D. C-1 of one glucopyranose and C-4 of fructofurnose