as we know strong acid has weak it conjugate base it means most stable conjugate base.
Then conjugates based give compounds -
Compound (A) is more stable than Compound (B) because presence of -Cl group in Compound (B) apply- I and +R effect, +R effect is more predominant than -I effect
∴ Compound (A) is more stable than (B) but Compound(C) is more stable than (A) because the negative charge is most stabilized by Highly electronegative atom.
Hence, order of acidity will be C > A > B.
