Answer:
a. A cost that is necessary for the overall operation of the business but not directly related to a contract
Explanation:
Option B - Allocable costs cannot be considered if the contractor is doing business with the government.
Option C - If the cost is exempted, it cannot be specifically allowable for a contract, or a cost that is beneficial to both the contract and other work.
Option D - Indirect costs cannot be allowable.
Option A - It is the right answer because allowable cost should be significant for the operations with an indirect relation with the contract. If it is linked with the overall operations, it can be considered as allowable to a contract.