• Reducing vs. Non-Reducing Disaccharides:
• reducing disaccharide contains at least one free anomeric carbon (hemiacetal or hemiketal group) capable of opening into an active carbonyl to reduce cupric ($Cu^{2+}$) ions:
• Maltose: Consists of two glucose units joined by an $\alpha(1\to 4)$ bond; the second glucose possesses a free anomeric $\text{C-1}$ $\to$ reducing.
• Lactose: Consists of galactose and glucose joined by a $\beta(1\to 4)$ bond; glucose retains a free anomeric $\text{C-1}$ $\to$ reducing.
• Non-Reducing Disaccharides:
• Sucrose: $\alpha\text{-D-Glc-}(1\leftrightarrow 2)\text{-}\beta\text{-D-Fru}$; anomeric carbons of both units are tied in the glycosidic bond $\to$ non-reducing.
• Trehalose: $\alpha\text{-D-Glc-}(1\leftrightarrow 1)\text{-}\alpha\text{-D-Glc}$; both anomeric carbons are engaged in the glycosidic linkage $\to$ non-reducing.
• Conclusion: Therefore, (B) and (C) only are reducing sugars.

Correct option: (2) (B) and (C) only.