Question: Which addition of the UEFA European Championship is the 2018–19 UEFA Nations League part of the qualification for?

Context articles: UEFA Euro 2020 qualifying
Sport in Belgium
2018–19 UEFA Nations League B
2018–19 UEFA Nations League C
Cristiano Ronaldo
2018–19 UEFA Nations League D
2018–19 UEFA Nations League
UEFA Euro 2020
2018–19 UEFA Nations League A
Wales at the UEFA European Championship

The UEFA Euro 2020 qualifying tournament is an upcoming football competition that will be played from March 2019 to March 2020 to determine the 24 UEFA member men's national teams that will enter into the UEFA Euro 2020 final tournament.
 The competition will be linked with the 2018–19 edition of the UEFA Nations League, giving countries a secondary route to qualify for the final tournament.
 For the first time since 1976, no team will automatically qualify for the UEFA European Championship as the host country.
Sport in Belgium plays a prominent role in the society.
 As of 2010, Belgium counted around 17,000 sport clubs with approximately 1.35 million members, thus 13% of the Belgian population is involved in sport.
 Popular sports in Belgium are among others football, cycling, tennis, table tennis, athletics, swimming, basketball, badminton, judo, hockey, motocross, auto racing, volleyball and running.
 Belgium has organized the 1920 Olympic Games in Antwerp as well as the 1972 UEFA European Championship and the 2000 UEFA European Championship along with the Netherlands.
 The Belgium national football team best result was a 4th place at the 1986 FIFA World Cup and a second place of the 1980 UEFA European Championship.
 Belgian football clubs have won 3 times the UEFA Cup Winners Cup and twice the UEFA Cup, plus 3 times the UEFA Supercup.
The 2018–19 UEFA Nations League B will be the second division of the 2018–19 edition of the UEFA Nations League, the inaugural season of the international football competition involving the men's national teams of the 55 member associations of UEFA.
The 2018–19 UEFA Nations League C will be the third division of the 2018–19 edition of the UEFA Nations League, the inaugural season of the international football competition involving the men's national teams of the 55 member associations of UEFA.
Cristiano Ronaldo dos Santos Aveiro (] ; born 5 February 1985) is a Portuguese professional footballer who plays as a forward for Spanish club Real Madrid and the Portugal national team.
 Often considered the best player in the world and widely regarded as one of the greatest of all time, Ronaldo has four FIFA Ballon d'Or awards, the most for a European player, and is the first player in history to win four European Golden Shoes.
 He has won 24 trophies in his career, including five league titles, four UEFA Champions League titles and one UEFA European Championship.
 A prolific goalscorer, Ronaldo holds the records for most official goals scored in the top five European leagues (372), the UEFA Champions League (109) and the UEFA European Championship (29), as well as the most goals scored in a UEFA Champions League season (17).
 He has scored more than 600 senior career goals for club and country.
The 2018–19 UEFA Nations League D will be the fourth and lowest division of the 2018–19 edition of the UEFA Nations League, the inaugural season of the international football competition involving the men's national teams of the 55 member associations of UEFA.
The 2018–19 UEFA Nations League will be the inaugural season of the UEFA Nations League, a planned international association football competition involving the men's national teams of the 55 member associations of UEFA.
 The competition, which will be held from September to November 2018 (pool stage) and June 2019 (Nations League Finals), will also serve as part of the qualification process for UEFA Euro 2020, awarding berths in the play-offs which will decide four of the twenty-four final tournament slots.
The 2020 UEFA European Football Championship, commonly referred to as UEFA Euro 2020 or simply Euro 2020, will be the 16th edition of the UEFA European Championship, the quadrennial international men's football championship of Europe organized by UEFA.
The 2018–19 UEFA Nations League A will be the top division of the 2018–19 edition of the UEFA Nations League, the inaugural season of the international football competition involving the men's national teams of the 55 member associations of UEFA.
 League A will culminate with the Nations League Finals in June 2019 to crown the inaugural champions of the UEFA Nations League.
This is a record of Wales' results at the UEFA European Championship.
 The UEFA European Championship, previously known at European Nations' Cup, is an international association football competition contested by the men's national teams of the members of "Union of European Football Associations" (UEFA), the administrative body for association football in Europe.
 The championship has been awarded every four years, since the first tournament in 1960.