For A) to D), Identify :

1- the nature of the configurational or conformational relationship.

2- The carbon with which a chemical bond must be broken to convert the two sugars (one into the other and vice versa) which are shown below.

 

A) Convert the 2' endo conformation to the 2' exo conformation of a b-L-ribofuranose.

B) Convert a D-aldohexose to a L-aldohexose.

C) Convert a Beta-D-aldohexose to an Alpha-D-aldohexose.

D) Convert D-galactose to D-glucose

It is all about arrangement of chiral carbon atoms. please see the explanations.

Step-by-step explanation

A) 2' endo conformation and 2' exo conformation of a b-L-ribofuranose are diastereoisomers of each other.

B) D-aldohexose and  L-aldohexose are stereoisomers of each other.

     They have same configuration but the D form can rotate the plane polarized light in clockwise direction where the  L form can rotate the plane polarized light in clockwise direction.

C) Beta D-aldohexose and Alpha D-aldohexose are anomers.

     They differ in configuration of carbon atom no 1, in Beta form the OH(hydroxyl) group of 1st carbon atom is at same plane with respect to 5th carbon atom and in it's Alpha form the OH(hydroxyl) group of 1st carbon is at different or opposite plane with respect to 5th carbon atom.

D) D-galactose and D-glucose are epimer of each other.

     Because they differ at carbon atom no-4.