Answer:
A. $0.
Explanation:
Tax Basis means that the acquisition cost plus any other cost incurred to make use of that asset. In this case tax basis of trailer is $12,000 but had been owned by Rego for 3 years which means it must have been depreciated over these 3 years. So, if the trailer is sold for $10,000 it must have profit and not any loss, so the allowable loss for Rego would be $0.