The correct answer is: A. One single overhead absorption rate for the whole factory.
A blanket overhead rate is a single rate that is used to allocate overhead costs to all products or services produced by a company. This rate is calculated by dividing the total overhead costs by the total number of units produced.
Option B is incorrect because a blanket overhead rate is not a blank or nil rate. It is a rate that is used to allocate overhead costs to products or services.
Option C is incorrect because a blanket overhead rate does not calculate multiple overhead rates for each production department, service department, etc. It is a single rate that is used to allocate overhead costs to all products or services produced by a company.
Option D is incorrect because a blanket overhead rate is not always a machine hour rate. It can be any type of rate, such as a direct labor hour rate or a unit of production rate.