The correct order of increasing basicity of the given conjugate bases $(\mathrm{R} \equiv {\mathrm{CH}}_3 )$ is

The conjugate acids of the given bases are $\mathrm{RCOOH},\mathrm{HC}\equiv \mathrm{CH},{\mathrm{NH}}_3$ and ${\mathrm{CH}}_4$ . The order of acidity of these acids is $\mathrm{RCOOH}>\mathrm{CH}\equiv \mathrm{CH}>{\mathrm{NH}}_3>{\mathrm{CH}}_4\text{. }$. Their conjugate bases will follow the reverse order, i.e. ${\mathrm{RCOO}}^{-}<{\mathrm{HC}}^{\mathrm{\prime }}\equiv {\mathrm{C}}^{-}<{\mathrm{NH}}_2^{-}<{\mathrm{CH}}_3^{-}$