Britain began imposing a 14-day quarantine Monday on travelers coming into the country — a sweeping measure meant to halt the further spread of COVID-19 that has been roundly criticized by the tourism industry. Authorities had no immediate answers as to why the 14-day quarantine wasn’t put in place on March 23, when Britain began its lockdown, or why an exception was made for attending the funeral of a close family relative when funerals are known to be virus-spreading events.