The correct option is B Fructose
Option (b)
Sugar Relative sweetness order-
Sucrose 100
Glucose 74
Lactose 16
Fructose 173
From this, it is clear that Fructose is the sweetest.
You might have guessed it's either Sucrose and Fructose from experience, but between these 2 we will need some proper experimental techniques to determine which is the sweeter one.