Which One of These Instructions to the Research Subject Will

Which one of these instructions to the research subject will provide the highest possible level of measurement?

A) Indicate whether your income is above $20,000 a year or not.
B) What was your income last year: 0 to $20,000; $20,000 to $60,000; $60,000 to $100,000; or more than $100,000?
C) What was your total income last year, before taxes? Enter amount: _______
D) Did you earn money last year?