A   Gal(1-4)Glc
beta-glycosidic bond.
4-(-D-galactopyranosyl)--D-glucopyranose

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B Glc(1-4)Glc
alpha-glycosidic bond.
4-(-D-glucopyranosyl)--D-glucopyranose

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C Glc(1-2)Psicose
alpha-glycosidic bond of glucose, beta-glycosidic of psicose.
-D-glucopyranosyl--D-psicofuranoside

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D  
non-glycosidic bond, this is not strictly a carbohydrate, due to the linking CH₂; in addition, since the anomeric -OH is missing, the two units are not monosaccharides.