After methylated D-sorbofuranose is hydrolyzed, what do the results imply about the relationship between D-sorbofuranose and D-sorbose?

D-sorbose is the acetal form of d-sorbofuranose because its ketone at C2 was used to react with it's C6 OH.

D-sorbofuranose is the acetal form of d-sorbose because its ketone at C1 was used to react with it's C5 OH.

D-sorbofuranose is the hemiacetal form of d-sorbose because its ketone at C2 was used to react with it's C5 OH.

D-sorbose is the hemiacetal form of d-sorbofuranose because its ketone at C2 was used to react with it's C6 OH.