[Mary1984]

Which of the following 3-carbon molecules has the greatest number of hydrogens?
A. propane
B. propanol
C. glycerol
D. none of the above

[TheUnassuming]

You might want to read the forum rules.
That said, what are the structures of the three compounds listed? 

[Mary1984]

You might want to read the forum rules.
That said, what are the structures of the three compounds listed?

I know that all of them are basically carbon and hydrogen bonds. but for propanol for example an OH bond has been added to the carbon-hydrogen structure. But what I am not sure about glycerol is that is it considered a sugar and if I amke sure that it is a sugar I know that the number of hydrogen is double times that number of hydrogen in the other two

[TheUnassuming]

Being a sugar doesn't mean it has 2x the number of hydrogens.

OK, so start by drawing the structures out on paper.  Then count the total number of hydrogens with each structure.
 
So for example ethanol is CH3CH2OH, which gives you 6 hydrogens. 

[Babcock_Hall]

Glyceraldehyde is a carbohydrate (probably OK to take that as a synonym for sugar).  Glycerol is a polyol, but I would not call it a carbohydrate.