What Is the Difference Between α-D-Glucose and α-D-Galactose

What is the difference between α-D-glucose and α-D-galactose?

A) They are mirror images of each other.
B) They differ in the configuration of substituents at C-4.
C) One is an aldose and the other is a ketose.
D) They are anomers.
E) One forms only O-glycosidic bonds, and the other forms only N-glycosidic bonds.