# How can I highlight this item of an enumerated list? [duplicate]

How could I hightlight an item from an enumerated list just like this is from the following picture?

\documentclass[12pt,a4paper]{article}
\usepackage{enumerate}
\usepackage{tikz}
\usepackage{mdframed}
\usepackage{type1cm}
\usepackage{lettrine}
\usepackage[listings]{tcolorbox}
\usepackage{color}
\begin{document}
\begin{enumerate}
\item 12
\item 143
\item 154
\end{enumerate}
\end{document}


A minimal working code be this one above.

If the lists are as simple that the one you have shown a rather easy solution is to define your own \item commands. One for highlighting and one for no highlighting.

\documentclass[12pt,a4paper]{article}
\usepackage{xcolor,soul}
\begin{document}
\makeatletter
\renewcommand\theenumi{\@Roman\c@enumi.}
\long\def\Item#1\par{%
\stepcounter{enumi}%
\leavevmode\makebox[2em]{\theenumi} #1%
\vskip4\p@ \@plus2\p@ \@minus\p@
}
\long\def\hItem#1\par{%
\stepcounter{enumi}%
\leavevmode\makebox[2em]{\hl\theenumi}\hl{ #1}%
\vskip4\p@ \@plus2\p@ \@minus\p@
}
\newenvironment{hlroman}{\quote\setcounter{enumi}{0}}
{\endquote}

\begin{hlroman}
\hItem A\par
\Item B\par
\Item C\par
\end{hlroman}
\end{document}


Feel free as an exercise to improve, by adding \leftkskip, \rightskip or hangindent to suit. Add complexity as needed (see for sample source2e 228).

I have used the soul package for highlighting.