鼠的毛色类型由等位基因Bb控制，甲、乙黑毛鼠分别与褐毛雄鼠丙交配，甲三胎生出9只黑毛幼鼠和7只褐毛幼鼠，乙三胎共生出19只黑毛幼鼠，则甲、乙、丙三只亲鼠的基因型依次为(    )
A.BB、Bb、bb                       
B.bb、Bb、BB
C.Bb、BB、bb                                                                   
D.Bb、bb、BB