$4)$ What is the time complexity function $($T$($n$)$ for the recursive algorithm below? F$1($n$,$ key$)\{$ if$($n$<1)$ return $0$; else F$1($n$-1,$ key$)$; $\}$ A$)$ T$($n$)=$T$($n$-2)+$c B$)$ T$($n$)=2$T$($n$-1)+$c C$)$ T$($n$)=($n$-1)+2$c D$)$ T$($n$)=$T$($n$+1)+$c E$)$ T$($n$)=2$T$($n$+1)+2$c