Carnival is an explosion of joy. It is a festival that mixes creativity, color1s, sounds, costumes  and so on.    The carnival in Rio  starts on Saturday, and ends on Tuesday.    Little need to be said about the carnival in Rio. Every year, Rio hosts the world's largest carnival. The samba school parades are world-famous.    The festival begins officially when the city's mayor hands over a giant silver and gold key to the Fat King (King Momo) . Then people dance, sing, party and have tons of fun. There are many parties that take lace before, during and after the carnival all night and all day.    Samba schools are not teaching institutions as their names suggests and do not offer samba classes.There are over 70 samba schools in Rio de Janeiro and they all parade during the 4-day celebration.They are organized into six competitive leagues.They are the Special Group A,B,C,Dand E.The first three groups parade in the Sambodromo.The other groups parade on the streets and are free to watch and join in.The biggest and most popular 12 leading schools are from the Special Group.They create a pageant with 3,000 to 5,000 people competing in the Samba Parade in the Sambodromo on Carnival Sunday and Monday. Balls takes place every night throughout the week, together with a variety of costume contests.    One of the most frequent questions we hear is " What is the date of the carnival this year?" Well, believe it or not , it is not an easy question to answer. You have to be part astrologer  , part mathematician, and part priest. The carnival in Rio will begin officially when  _
the mayor announces officially King Momo appears King Momo takes over the key of the city. the mayor comes with the King Momo.
Question: Carnival is an explosion of joy. It is a festival that mixes creativity, color1s, sounds, costumes  and so on.    The carnival in Rio  starts on Saturday, and ends on Tuesday.    Little need to be said about the carnival in Rio. Every year, Rio hosts the world's largest carnival. The samba school parades are world-famous.    The festival begins officially when the city's mayor hands over a giant silver and gold key to the Fat King (King Momo) . Then people dance, sing, party and have tons of fun. There are many parties that take lace before, during and after the carnival all night and all day.    Samba schools are not teaching institutions as their names suggests and do not offer samba classes.There are over 70 samba schools in Rio de Janeiro and they all parade during the 4-day celebration.They are organized into six competitive leagues.They are the Special Group A,B,C,Dand E.The first three groups parade in the Sambodromo.The other groups parade on the streets and are free to watch and join in.The biggest and most popular 12 leading schools are from the Special Group.They create a pageant with 3,000 to 5,000 people competing in the Samba Parade in the Sambodromo on Carnival Sunday and Monday. Balls takes place every night throughout the week, together with a variety of costume contests.    One of the most frequent questions we hear is " What is the date of the carnival this year?" Well, believe it or not , it is not an easy question to answer. You have to be part astrologer  , part mathematician, and part priest. The carnival in Rio will begin officially when  _
A. the mayor announces officially
B. King Momo appears
C. King Momo takes over the key of the city.
D. the mayor comes with the King Momo.
Answer: