Which of the following countries was in 2011 the only one to have obligatory sex education in schools?

Explanation

Not all European countries have obligatory sex education in school. The following countries do, however: Austria (1970), Belgium (1995), Czech Republic (1970), Denmark (1970), Estonia (1996), Finland (1970), France (1998), Germany (1968), Greece (1995), Hungary (1974), Iceland (1975), Ireland (2003), Latvia (1998), Luxembourg (1973), Netherlands (1993), Norway (1974), Portugal (1999), Slovakia (1996) and Sweden (1955).