Q: Side-by-Side figures with subfigures in a single-column text format I want to place 2 figures side-by-side in a single column document written using elsarticle where each figure has some sub-figures associated with it.

Here is my mwe
\documentclass[review]{elsarticle}
\usepackage{subfig}
\begin{document}
    \begin{figure}[]  % Figure 1
        \centering
        \subfloat[A]{\includegraphics[width=0.4\linewidth,height=0.15 \textheight]{example-image-a}} \\
        \subfloat[B]{\includegraphics[width=0.4\linewidth,height=0.15 \textheight]{example-image-b}} \\
        \caption[]{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque }
    \end{figure}
    
    \begin{figure}[]  % Figure 2
        \centering
        \subfloat[C]{\includegraphics[width=0.4\linewidth,height=0.15 \textheight]{example-image-c}} \\
        \subfloat[X]{\includegraphics[width=0.4\linewidth,height=0.15 \textheight]{example-image}} \\
        \caption[]{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque }
    \end{figure}
\end{document}

can someone help me place them the way they look in the attached image?

A: You need to put both images in one figure float, each in minipage or intabularx:
With minipage:
\documentclass[review]{elsarticle}
\usepackage{subfig}
\begin{document}
    \begin{figure}[ht]  
        \setkeys{Gin}{width=0.4\linewidth,height=0.15\textheight}
    % Figure 1
    \begin{minipage}[t]{0.45\linewidth}
        \centering
        \subfloat[A]{\includegraphics{example-image-a}} \\
        \subfloat[B]{\includegraphics{example-image-b}} 
        \caption[]{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque }
    \end{minipage}
    \quad
    \begin{minipage}[t]{0.45\linewidth}
        \centering
        \subfloat[C]{\includegraphics{example-image-c}} \\
        \subfloat[X]{\includegraphics{example-image}} 
        \caption[]{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque }
    \end{minipage}
    \end{figure}
\end{document}


With tabularx:
\documentclass[review]{elsarticle}
\usepackage{subfig}
\usepackage{tabularx}
\newcolumntype{C}{>{\centering\arraybackslash}X}

\begin{document}
    \begin{figure}[ht]  
        \setkeys{Gin}{width=0.4\linewidth,height=0.15\textheight}
    % Figure 1
    \begin{tabularx}{\linewidth}{CC}
        \subfloat[A]{\includegraphics{example-image-a}}
        
        \subfloat[B]{\includegraphics{example-image-b}} 
        \caption[]{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque }
    &
        \subfloat[C]{\includegraphics{example-image-c}} 
        
        \subfloat[X]{\includegraphics{example-image}} 
        \caption[]{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque }
    \end{tabularx}
    \end{figure}
\end{document}

Result is similar as before.
