[tex]\boxed{B.\:5x\:+\:12}[/tex]
[tex]\large\mathfrak{{\pmb{\underline{\red{Step-by-step\:explanation}}{\orange{:}}}}}[/tex]
[tex]4 + x + x + 2x + 5 + 3 + x \\ = (x + x + 2x + x) + 12 \\ since \: they \: are \: like \: terms, \: we \: can \: add \: them \\ = 5x + 12[/tex]
[tex]\large\mathfrak{{\pmb{\underline{\orange{Happy\:learning }}{\orange{.}}}}}[/tex]
