The correct answer is option 3: Fructose. Fructose is considered the sweetest sugar compared to the other options.

1. Sucrose is a combination of glucose and fructose, and while it is sweet, it is not as sweet as fructose on its own.

2. Glucose is a common sugar and is less sweet compared to fructose.

3. Fructose is naturally found in fruits and is known to have the highest level of sweetness among all sugars.

4. Maltose is a sugar made up of two glucose molecules and is not as sweet as fructose.

It is important to note that sweetness is subjective and can vary based on individual taste preferences. However, in general, fructose is considered the sweetest sugar.