There are two character strings：s and t.s="My favor is computer"，t=substr(s，9，5)．Then the result after operation is( )。

A．S="My favor is computer"；　　t="compu"；
B．S="My favor is computer"；　　t="is co"；
C．S="My favor"；　　　　　　　　 t="is co"；
D． S="My favor"；　　　　　　　　 t="is computer"；