Which of the following costs is NOT relevant to a make-or-buy decision?

Select one:

$10,000 of used to manufacture the parts.

$30,000 of depreciation on the equipment used to manufacture the parts.

The supervisor's salary of $25,000, which would be avoided if the part is purchased from an outside supplier.

$15,000 in rent from leasing the production space to another company if the part is purchased from an outside supplier.