The correct order of acidic strength among the following is

Acidity is directly proportional to the $-\mathrm{I},-\mathrm{M}$ effect. The $-\mathrm{I}$ effect of the fluorine atom is higher than the chlorine atom. So, the ${\mathrm{FCH}}_2{\mathrm{CO}}_2\mathrm{H}$ has more acidity than the ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CHClCO}}_2\mathrm{H}$. The benzoic acid has more acidic strength than the acetic acid because phenyl group show the $-\mathrm{I}$ effect but methyl group will show the $+\mathrm{I}$ effect. 

So, the acidity order is :-

${\mathrm{FCH}}_2{\mathrm{CO}}_2\mathrm{H}>{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CHClCO}}_2\mathrm{H}>{\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CO}}_2\mathrm{H}>{\mathrm{CH}}_3{\mathrm{CO}}_2\mathrm{H}$