All of the following are true with regard to the alternative depreciation system except:

a. once the ADS election is made for specified property, it is irrevocable

b. the ADS election is available to personal property on a property by property basis

c. the ADS election is available to real property on a property by property basis

d. the principal type of property for which ADS is required is any tangible property which is used predominantly outside of the U.S.