The structural formula for a carbohydrate molecule may be represented as: (a Fischer projection with an aldehyde group $\text{C}=\text{O}$ at the top, a carbon chain with alternating $\text{H}$ and $\text{OH}$ side groups, and a terminal $\text{CH}_2\text{OH}$ group.) Which of the molecules could be shown by this formula?
- A1 only
- B2 only
- C2 and 3 only
- D1, 2 and 3