When glycerol is treated with excess of HI, it produces: allyl iodide, 2-iodopropane, glycerol triiodide, propene

When glycerol is treated with an excess of HI, it produces 2-iodopropane.
In the first step, a molecule of glycerol reacts with 3 HI molecules to form unstable 1,2,3-triiodopropane. This loses a molecule of iodine to form allyl iodide.
Allyl iodide adds a molecule of HI to obtain an unstable molecule which loses a molecule of iodine to form propene.
A molecule of HI is added to propene to form 2-iodopropane.
Hence, the correct option is B (2-iodopropane).