Which amongst the following is the strongest acid?

Acidic character $\text{α}$ stability of conjugate base (anion)

Stability of anion $\text{α}-M$ and $–I$

$-M>-I\left(\text{dominance}\right)$

Electron withdrawing groups increase acidic strength. Among the given compounds, the electron withdrawing strength of substituents

In case of halogen $-\mathrm{I}>+\mathrm{M}$ and $-\mathrm{I}$ order of halogen $\mathrm{Cl}>\mathrm{Br}>\mathrm{I}$

Hence, $CH{\left(CN\right)}_3$ will be most acidic