The requirement generally will be triggered by a request from an individual with a disability, who frequently can suggest an appropriate accommodation. Accommodations must be made on a case-by-case basis, because the nature and extent of a disabling condition and the requirements of the job will vary. The principal test in selecting a particular type of accommodation is that of effectiveness, i.e., whether the accommodation will enable the person with a disability to perform the essential functions of the job. It need not be the best accommodation or the accommodation the individual with a disability would prefer, although consideration is given to the preference of the individual involved. However, the local senior management official serving as the Decision-maker will have final discretion to choose between effective accommodations, and s/he may select one that is least expensive or easier to provide.