Is it minimal?

Let M be a DFA with alphabet $\{$a$,$ b$\},$ state set $\{$p$,$ q$,$ r$,$ s$\},$ start state p$,$ final state set $\{$q$,$ s$\},$ and transition function $\backslash$delta $($p$,$ a$)=$ p$,\backslash$delta $($p$,$ b$)=$ q$,\backslash$delta $($q$,$ a$)=$ q$,\backslash$delta $($q$,$ b$)=$ r$,\backslash$delta $($r$,$ a$)=$ r$,\backslash$delta $($r$,$ b$)=$ s$,\backslash$delta $($s$,$ a$)=$ s$,$ and $\backslash$delta $($s$,$ b$)=$ p$.$ Then M is a minimal DFA. true or false