Which among the following is the simplest sugar?

The correct corresponding order of names of four aldoses with configurations given below,respectively,is:
$(1)$ $CHO-CH(OH)-CH(OH)-CH_2OH$ (both $-OH$ on right)
$(2)$ $CHO-CH(OH)-CH(OH)-CH_2OH$ ($-OH$ on left at $C-2$,right at $C-3$)
$(3)$ $CHO-CH(OH)-CH(OH)-CH_2OH$ (both $-OH$ on left)
$(4)$ $CHO-CH(OH)-CH(OH)-CH_2OH$ ($-OH$ on right at $C-2$,left at $C-3$)

Glycogen is a branched chain polymer of $\alpha-D$-glucose units in which the chain is formed by $C_1-C_4$ glycosidic linkage,whereas branching occurs by the formation of $C_1-C_6$ glycosidic linkage. The structure of glycogen is similar to:

When amylases catalyse the hydrolysis of starch,the final product obtained is chiefly

Compound $A$ gives $D$-Galactose and $D$-Glucose on hydrolysis. The compound $A$ is:

Consider the following molecules:
Glucose $(K)$,Mannose $(L)$,Galactose $(M)$,$\alpha-Glucose$ $(N)$,$\beta-Glucose$ $(O)$
The correct set of epimer and anomer is respectively:
Epimer - Anomer