Aluminium is added in Bessemer process to remove certain impurities, but not in $L-D$ process. This is because:

The correct option is D pure oxygen is passed in $L-D$ process
The main impurity in Pig Iron is carbon. In Bessemer process, the carbon converts to $A{l}_4{C}_3$ by adding aluminium to it. But in $L-D$ process, pure oxygen is passed. So carbon converts to $C{O}_2$ and goes away from Pig Iron.