Identify what is being asked

We need to classify the given carbohydrate from the options:

• ketohexose
• aldohexose
• $\alpha$-furanose
• $\alpha$-pyranose

Use structural clues

Such questions are usually based on whether the sugar is shown in:

• open-chain form or cyclic form
• whether it contains an aldehyde group or ketone group

Check for aldehyde vs ketone

• An aldohexose has:
  • 6 carbon atoms
  • an aldehyde group at one end in the open-chain form
• A ketohexose has:
  • 6 carbon atoms
  • a ketone group, usually at C-2

The carbohydrate shown corresponds to a sugar having an aldehyde functional group and six carbons, so it is an aldohexose.

Reject cyclic-form options

Options $C$ and $D$ refer to cyclic structures:

• furanose $\rightarrow$ 5-membered ring
• pyranose $\rightarrow$ 6-membered ring
• $\alpha$ refers to the orientation at the anomeric carbon

Since the structure is identified as the open-chain aldehyde form, these cyclic descriptions do not apply.

Reject ketohexose

Since the carbonyl is aldehydic and not ketonic, option $A$ is incorrect.

Final answer

Therefore, the carbohydrate is an aldohexose.