Which of the following compounds does not give a test with ninhydrin but gives a positive test with Benedict's solution?

Considering the facts that
$I$. sucrose forms glycosidic linkage between $C_1$ of glucose and $C_2$ of fructose,while
$II$. lactose forms glycosidic linkage between $C_1$ of galactose and $C_4$ of glucose.
Choose the correct statement.

Which of the following cannot be used to distinguish between glucose and fructose?

Assertion : Sucrose is a non-reducing sugar.
Reason : It has glycosidic linkage.

Which of the following are reducing sugars?
$(A)$ Sucrose,$(B)$ Maltose,$(C)$ Lactose,$(D)$ Fructose

Find the number of optical isomers for the compound $CHO-CH(OH)-CH(OH)-CH(OH)-CH(OH)-CH_2OH$.