请选择DCBA,`'n.z2O4E'{4e7n;p9T0d8x*y2d3F It is chairman of the department _________ the teaching staff elected him.4I(o-Y3w;F+N(r0`8h
A.what4I(o-Y3w;F+N(r0`8h
B.whom4I(o-Y3w;F+N(r0`8h
C.which4I(o-Y3w;F+N(r0`8h
D.that4I(o-Y3w;F+N(r0`8h