Which $L$-sugar on oxidation gives an optically active dibasic acid?

Given below are two statements:
Statement $I$: Sucrose is dextrorotatory. However, sucrose upon hydrolysis gives a solution having a mixture of products. This solution shows laevorotation.
Statement $II$: Hydrolysis of sucrose gives glucose and fructose. Since the laevorotation of glucose is more than the dextrorotation of fructose, the resulting solution becomes laevorotatory.
In the light of the above statements, choose the correct answer from the options given below.

Identify the trisaccharide from the following.

What is the product formed when sucrose is treated with concentrated sulfuric acid $(H_2SO_4)$?

The formulas of $A$ and $B$ for the following reaction sequence are:

Identify the glycosidic linkage present in lactose.