X. A sunk XXXX XX a XXXXXXXXXXXXX (XXXX) cost that has already been incurred and XXXXXX be recovered. Sunk costs XXX XXXXXXXXX contrasted with XXXXXXXXXXX costs XXXXX as marginal cost XX the change in the total XXXX that arises XXXX the quantity XXXXXXXX has an increment XX unit. XXXX XX, it is XXX cost of producing one more XXXX XX a XXXX. XX XXXXXXX XXXXX, XXXXXXXX cost XX XXXX level of production XXXXXXXX XXX additional costs XXXXXXXX to XXXXXXX the next unit.