II$.$ Working backwards to the original carbonyl compound and Grignard Reagent.

Worked Example

Look at the carbon where the $OH$ group is bonded and sever the bond between it and the nextdoor neighbor carbon. The side of this bond with the $OH$ group was the original carbonyl compound, and the other side was the Grignard. obrace$({)}^{+MgBr}$

For each of the following alcohols, identify the new $C-C$ bonds and work backwards to the starting carbonyl compound and Grignard reagent as was done in the worked example.