请选择CBA9w;D.`4@*\:r9h/hPlease be quiet! Dad ______ working in the room.;y'A4t)p,O6}.j7{)c4}
A. am;y'A4t)p,O6}.j7{)c4}
B. is;y'A4t)p,O6}.j7{)c4}
C. are;y'A4t)p,O6}.j7{)c4}