Which of the following is the first member of monosaccharides?

What is obtained from the hydrolysis of maltose?

Chitin present in the exoskeletons of arthropods is

In the given structural formula,what does $A$ indicate?

Identify the biological importance of carbohydrates from the following statements:
$1$. In the structure of cell wall.
$2$. As a food storage substance.
$3$. In protein synthesis.
$4$. As enzymes.
$5$. In the structure of $DNA$.

Select the correct option indicating the products of the following reaction:
Lactose $\xrightarrow{\text{Lactase}}$ $\square$ + $\square$