[schan1]

Hey
I am struggling with a question. Can anyone explain it to me?

Which one of the following acids is the second strongest acid?
a. HOClO3
B. HOClO2CH3
C. HOClFO2
D. HOCl(CH2F)2I
E. HOClF3

The answer is C. I tried to calculate the electronegativity of Y in the bond of HOCl ----Y, but I don't get the answer. Is there any other ways to solve this problem? genius plz help me!!