D-fructose is a ketohexose that, upon reduction, yields a sugar alcohol identical to the one obtained from the reduction of D-mannose. Given this relationship between D-fructose and D-mannose, suggest the structure of this common sugar alcohol product. (Hint: When aldohexose and ketohexose are reduced, CH₂OH groups are present at both ends. Any one of these primary alcohol groups may have originated from an aldehyde reduction.)