The letter 'D' or 'L' before the name of a stereoisomer of a compound indicate the correlation of configuration of that particular stereoisomer.
This refers to their relation with one of the isomers of glyceraldehyde. Predict whether the following compound as 'D' or 'L' configuration.
Since the -OH group at the penultimate chiral carbon atom (i.e., last but one or C5 ) is towards left.
Here, OH group present on second last carbon in at left side hence this has L - configuration.