Resposta :
[tex]\textsf{Letra D}[/tex]
Explicação passo a passo:
fórmula:
[tex]\Large\boxed{\begin{array}{l} \Large\boxed{\begin{array}{l} \sf{S_i = (n - 2) \: . \: 180 {}^{ \circ} \rightarrow \begin{cases} \sf \: S_i = somar \,dos \,\hat{a}ngulos\, internos \\ \sf \: n =n\acute{u}mero\,de\, lados \end{cases}}\end{array}}\end{array}}[/tex]
Cálculos:
[tex] \Large\boxed{\begin{array}{l} \Large\boxed{\begin{array}{l} \sf \:S_i = (n - 2) \: . \: 180 {}^{ \circ} \\ \\ \sf \:S_i = (5 - 2) \: . \: 180 {}^{ \circ} \\ \\ \sf \:S_i = 3 \: . \: 180 {}^{ \circ} \\ \\ \red{\boxed{ \boxed{ \sf{ \: \therefore \: S_i = 540 {}^{ \circ} \: }}}}\end{array}} \end{array}}[/tex]