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I understand that the compound above is a ketose because it has a furanose ring. But, how do we know that it is a "D" form?

Is there any general rule by which I can identify if any given aldose/ketose is in D/L form?

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Your structure is a ketose because it is a hemiketal of a ketone. It is a furanose because it is a 5-membered (furan-oid) ring. Fructose, which your structure is not, is usually drawn as a furanose as in sucrose but fructose itself exists principally in the pyranose (6-membered ring) form.
How do you recognize the D-configuration? Your furanose 1a is in the D-series. Reverse your furanose to the keto form 1b by following the red bonds. Rotate about the C4-C5 bond by 120o as illustrated by the blue arrow in 1b. This rotation produces the Fischer projection 1c having the C5-hydroxyl on the right. Thus, furanose 1a is of the D-series.
There is another method that can be used with qualification. At any carbon that determines D vs. L in a carbohydrate, as long as the substituents are O, CH2OH, CH(OH)C and H, the D-series will be of the R-configuration. Conversely, The L-series will be of the S-configuration. In furanose 1a, the priorities are O>C4>C6>H. This determination is easy using this method.
Structures 2a, 2b and 2c are different representations of α-D-glucose. All of the C5-carbons are, necessarily, of the R-configuration and therefore in the D-series.

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Structures 3a and 3b are Haworth renderings of sucrose. Both the glucose (pyranose) and fructose (furanose) moieties are of the R-configuration and in the D-series.

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