[tex]\large{\begin{array}{l}\sf V=\dfrac{\Delta S}{\Delta t}\Rightarrow\Delta t=\dfrac{\Delta S}{V}\\\\\sf \Delta t=\dfrac{4}{12}\\\\\sf \Delta t\approx0{,}333\,h\\\\\sf 1\,h\rightarrow60\,min\\\sf 0{,}333\,h\rightarrow t\\\\\sf t=\dfrac{60\cdot0{,}333}{1}\\\\\boxed{\boxed{\sf t\approx 20\,min}}\leftarrow\textsf{Letra B}\end{array}}[/tex]
