Final answer:
The method that may NOT be used to estimate reproduction cost is unit-in-place.
Step-by-step explanation:
The method that may NOT be used to estimate reproduction cost is c. unit-in-place. This method is not used to estimate reproduction cost, but rather to estimate the cost of replacing an existing asset with a new one. Quantity survey, economic age-life, and comparative unit are all methods that can be used to estimate reproduction cost.