Given the following three statements: $1.$ n$($n$+1)/2$ belongs to O$($n$)$ II$.$ n$($n$+1)/2$ belongs to O$($n$)$ III. n$($n$+1)/2$ belongs to $($n$)$ I, II$,$ and III are respectively a$.$ True, True, False b$.$ False, False, False c$.$ False, False, True d$.$ Ture, False, False e$.$ False, True, True