Passengers wait in the queues WT$-1,$ WT$-2$ and WT$-3$ until there is an agent, officer or X$-$ray lane available. What type of process control is this?A$.$ Pull control $($synchronized flow$),$ and consequently, WIP Levels are low.B$.$ Pull control $($synchronized flow$),$ and consequently, throughput times are long.C$.$ Push control $($decoupled$),$ and consequently, WIP levels are low.D$.$ Push control $($decoupled$),$ and consequently, throughput times are long$4.$