How long is the licence disqualification after one conviction?

Answer: B — 1 year

After one conviction, the licence disqualification is typically one year. Option A is incorrect because 6 months is a shorter period of time than 1 year. Option C and D are more severe and longer periods of time than one year, so they are also incorrect. It is important to follow traffic laws and avoid any convictions to prevent a longer licence disqualification.