Considere as funções reais

$f:{\mathbb{R}}_{+}^{\ast }\to \mathbb{R}$ tal que $f(x)=x-2$

$g:\mathbb{R}\to {\mathbb{R}}_{+}^{\ast }$ tal que $g(x)={\left(\frac{1}{2}\right)}^x$

$h:{\mathbb{R}}_{+}^{\ast }\to \mathbb{R}$ tal que $h(x)=-{\log }_{2}x$

e marque a alternativa correta