[boomtime]

I was hoping someone could help me figure out a way to attack problems set up similar to this one where you must pick the strongest acid or base, or order the acids and bases from strongest to weakest

-Which of the following is the strongest acid?
a.)CH3CO2H
b.)ClCH2CO2H
c.)Cl2CHCO2H
d.)Cl3CCO2H

Thanks in advance for the help I know it involves looking at what is bonded to the hydrogens and the elements electronegativity, but just have hit a block at trying to get the last chunk to figure it out. 

[Dan]

Here's a good website.