f is defined in [-5, 5] as f(x) = x if x is rational and = -x is irrational. Then

• A

  f(x) is continuous at every x, except x = 0
• Correct answer
  B

  f(x) is discontinuous at every x, except x = 0
• C

  f(x) is continuous everywhere
• D

  f(x) is discontinuous everywhere

Hence, the correct answer is option: 'B'.