During a chair flip, what happens to the substituents at carbon number 4 in a pyranose ring?

• A. Both axial and equatorial positions change, along with the up/down orientation.
• B. The equatorial position becomes axial, and the axial position becomes equatorial, with up/down orientation changing.
• C. The axial position becomes equatorial and vice versa, while the up/down orientation remains unchanged.
• D. The axial position remains axial, and the equatorial position remains equatorial.

Answer: (C)