Which of these groups of numbers would fall into the same equivalence class?

Which of these groups of numbers would fall into the same equivalence class?

In a system designed to work out the tax to be paid: An employee has £4000 of salary tax free. The next £1500 is taxed at 10% The next £28000 is taxed at 22% Any further amount is taxed at 40%

• A. £4800; £14000; £28000
• B. £5200; £5500; £28000
• C. £28001; £32000; £35000
• D. £5800; £28000; £32000

Answer: Option D