A work centre uses an average of $850$ parts per day. A standard sized container holds $160$ parts. On average it takes $\mathrm{.}30$ days for a contained to complete the circuit from a kanban being received until the container is returned full. If the policy is to use a safety stock of $20\%(\%$ of usage during the lead time$),$ how many kanbans should be used? $($rounding up to provide a relatively loose system$).$

Multiple Choice

$3$

$2$

$4$

$1$