Treat all acids with `Cl_2//P` or `Br_2//PBr(H.V.Z)` reaction.
(I) does not have `alpha-H` and would not react with `Cl_2//P`.
(II) has one `alpha-H` amd would give a monochlorinated product.
(III) has two `alpha-H` and would give a dichlorinated product.
The chlorine content in the chlorinated compound of `(B)` and `( C)` is determined by quantative methods.