DCR Ltd$.$ manufactures part XJ$14$L used in several of its engine models. Monthly per unit production costs for $1,000$ units are provided in the table below.

It is estimated that $10\%$ of the fixed overhead costs will no longer be incurred if the company buys XJ$14$L from an outside supplier. The cost to purchase XJ$14$L from the supplier is $$85$ per unit. If DCR purchases $1,000xJ14L$ parts from the outside supplier per month, its monthly net income will

a$.$ increase by $$13,000.$

b$.$ increase by $$15,000.$

c$.$ decrease by $$5,000.$

d$.$ decrease by $$3,000.$

$\backslash$table$[[$Direct materials,$$40\mathrm{.}00$