To solve this problem, we need to understand the difference between reducing and non-reducing sugars.$\newline$Reducing sugars are carbohydrates that can act as reducing agents due to the presence of a free aldehyde or ketone group.$\newline$Non-reducing sugars, on the other hand, do not have a free aldehyde or ketone group available for reduction.$\newline$Let's analyze each option:$\newline$• Option 1: Maltose is a reducing sugar because it has a free hemiacetal group.$\newline$• Option 2: Lactose is also a reducing sugar due to its free hemiacetal group.$\newline$• Option 3: Glucose is a reducing sugar as it contains a free aldehyde group in its open-chain form.$\newline$• Option 4: Sucrose is a non-reducing sugar because the glycosidic bond between glucose and fructose involves the anomeric carbons,$\newline$ leaving no free aldehyde or ketone group.$\newline$Therefore, the correct answer is Option 4: Sucrose.