Figure $519.$ Consider Figure $5.$ How would one refer to the attribute x in A from within a mettiod of B $?($a$)$ this. x$($b$)$ super, x$($c$)(($A$)$ this$).$ x$($d$)$ Both $($b$)$ and $($c$).($e$)$ It is impossible to refer to x in A from the class B$.$