Correct Answer - C
Start with a ring of three carbon atoms and then move to the ring of four carbon atoms.
underset("Propylene glycol")(CH_(3)overset(OH)overset(|)(CH)CH_(2)OH) underset("Glycerol")(HOCH_(2)overset(OH)overset(|)(CH)CH_(2)OH)`
Thus a total of seven alcohols (including stereoisomers) is possible.