Multiple Choice Question

The following quadratic multiproduct cost function: $C(Q_1,Q_2)=f+a{Q}_1{Q}_2+(Q_1{)}^2+(Q_2{)}^2$ exhibits cost complementarity when

$f-a{Q}_1{Q}_2<mn\; id="EditorElement\_590178">0</mn>$

$a>0$

$f-a{Q}_1{Q}_2>0$

$a<mn\; id="EditorElement\_590072">0</mn>$