Walsh Automobile Company fabricates automobiles. Each vehicle includes one airflow sensor$,$ which is currently made in $-$ house. Details of the airflow sensor fabrication are as follows:

$\backslash$table$[[$Volume$,800,$units per month$],[$Variable cost per unit,$$7\mathrm{.}00,$per unit$],[$Fixed costs,$$14,000,$per month$]]$

A Japanese factory has offered to supply Walsh with ready$-$made units for a cost of $$14$ per sensor$.$ Assume that Walsh's fixed costs could be reduced by $$5,000$ if it outsources and that Walsh will not be able to use the excess capacity in any profitable manner. If Walsh decides to outsource, monthly operating income will:

A$.$ decrease by $$600$

B$.$ increase by $$5,600$

C$.$ increase by $$14,000$

D$.$ decrease by $$14,000$