This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Best biochemical description of glucose is? 
Select and explain. 
A. Exists as ketose sugar, B. Present in L form in all biosystems, C. Its C-4 epimer is galactose, D. It's a disaccharide
C: Its C-4 epimer is galactose
Answer: C: Its C-4 epimer is galactose 
Explanation: Glucose:

Simple sugar (monosaccharides)
Has six carbon atoms (hexose)
Its C-4 epimer is galactose
Has 2 isomers - D-isomer (D-glucose/dextrose, occurs widely in nature) and L-isomer (L-glucose - does not occur much in nature)
It is stored as a polymer (in plants as starch and in animals as glycogen)