The cyclic sugar shown is converted back to its open-chain form by ring opening. Which statement describes the open-chain sugar?

The ring (five-membered, furanose) contains the former carbonyl carbon C-2, which carries OH, CH2OH and the ring oxygen. Opening gives a C=O at C-2 with six carbons, a ketohexose (D-fructose). The ring form has 4 stereocentres, but in the open chain C-2 is no longer one, leaving 3 (RDKit gives 3).