begin{easylist}[enumerate]
ListProperties(Hang=true, Margin=4em)
@ Do action 1
@ Choose between those two options:
    begin{easylist}[itemize]
    ListProperties(Hang=true, Margin=6em)
    @ either do A
    @ or do B
    end{easylist}
ListProperties(Margin=4em)
@ Do action 3
end{easylist}

documentclass{article}
usepackage[at]{easylist}

begin{document}

begin{easylist}[enumerate]
ListProperties(Hang=true, Margin=4em)
@ Do action 1
@ Choose between those two options:
    begin{easylist}[itemize]
    ListProperties(Hang=true, Margin=6em)
    @ either do A
    @ or do B
    end{easylist}
NewList(Start1=3,Margin=4em)
@ Do action 3
end{easylist}

end{document}